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GC864 Hardware User Guide

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2. VERIFIED Noms 080705 0276 2 5 30276SE11139A 1 2 3 4 6 8 9 10 11 43 7V PL201 4731955140400 4731955140400 2 y r TX TRACE EST TRACE 44 oT TG RX TRACE TRACE Le VBATT 5 9 2 SDA HW 4 0402 NES lg vearr a9 IIC GND 5 NG VBATT 59 SCL HW 6 R202 2 9 owe Ba e pa BG 5 5500 CLK 2 0402 PS ssco o eo 8 R203 2 5 a LB 7 E 7 a SSC SSCO MTSR 0402 55 0 MTSR ee GND lt o 5 11B L 88 0 MRST 2 sco o lg S 11B cider CHARGE CFR GND n ee CHARGE Le AR GND 3 5 lt GND Le GND E GND o 15 14 pron E dM kam CIO4 RXD ON OFF 21 C103 TXD Ci03 TXD 3 3C C108 DTR CIOS DTR RESET M RESET 9 3 3C 1 9 4 18 lt E 20 19 N lt CIO7 DSR TO CI07 DSR 3 2 a lt CIOS RTS C105 RTS 20 lo 3 3C C106 CTS 2 gt CI06 CTS STAT LED 2 STAT LED 3 3C 3E C125 RING a CI25RING 24 3 3C
3. 1 2 3 4 6 7 8 9 10 11 1 X501 NX1255GB 6 000MHz ee a Bas w M Bea coa h UEO gt 5 092 100nF 0504 2188 PET 34 BEES XSR AHCIGUD4DCKRGA 11 10v 3 d TH wa 0402 3 3V_HUB o R516 1 5K LTF R515 GND 0 5 FAM T4AHC1GU04DCKRG4 4 El 2 0504 4 Fr2232 i s o IN 3D 9C 2 506 o 4 LP2982AIM5X 3 3 502 33V HUB a 45V USB n 2 58 R510 e 2 lv our VIN 5V_USB a a a a MR a S0501 1 5K noMount YES GND USBE 004 o m 2 9 8 amp C512 JP501 5 9 ee PLO 100nF C513 4 BYPASS ON OFF 7 Kao e Sg E e lo 9019915102410 10uF N gt e E a isi pia v 10V Say 2 E S S8 z ay CONT A C514 LI9A dub 0603 2 Ha 2 O amp e 1 ppo 24 e 0402 pe GN 3 x 2 23 C 2 Sa NPINTI 25v T 4 QR E RSIT db 3 3 10502 pinto 22 8 0 aus 45V USB 2 777 C518 NE HUB 4 RESET TEXTUSB2036VERG4 OCPROT PWRSW a e e 0 mO 5 x GND 5 mH pps L20 e ssy use 9 5 amp 8 n 82 5 E S PQFP G32 e O 2 EEDATA GANGED DM3 O x 77 GND C519 m R505 TA
4. D 3V EXT MIG SINGLE Sus p714 ENEE Ba 0603 0701 m a GM8B2 MICH DECOUPLING CAPACITORS vs vm os 25 4 v no EP 2 i 4 Q C719 R715 2 1000F 47K NG ET ces TO MIC 1 TO m o make S 8 862 55182 SN SG Bus A GND GND 34 ENT MIG SINGLE E U701 Oy D 18391810 GM862_MIC 43v EXT SINGLE 1 5 227 R720 E m E E as ER x Mg 585 1 T o mS 0693 8 a E725 SEE m C720 R715 jin nF 2888 100nF Ark vey 317 16v P 15 bx 0693 1 0603 0609 D ENG ENG END The schematic does not include the required mic biasing circuitry For the biasing the same circuit as seen before can be used to be noticed that the capacitor C3 on the unbalanced biasing circuit is not anymore needed if this Buffered design is used Two different configurations are used one inverting and the other not inverting hence an additional 6dB 2 times gain is achieved by doubling the mic signal path The gain of the not inverting buffer is given by the formula Gain 1 B 720 and hence it cannot be less than 1 In the example shown
5. 1 2 4 5 6 7 8 9 10 11 E PL106 9019915102410 PL103 853 1984617PT1 5_2 3 5 H x SB s3 5 alan CURRENT UNLIMITED pa T Lal ne SI z 2 105 2 1 Pi BATTERY CHARGER INPUT R105 4 5 PEP 5 CHARGER ON 1 680 7 sov NG 6 Vec A 0603 s ES Bl ws 5 R113 8 a 0603 ON OFF 2 5 2 98 2 OUT BCR185W R108 Q105 680 596 ae 5 1 0603 3 M676 3Fs NN RS s UU Nx Eur e 8 432N BC857B 2 A WARNING LY M676 Q251 26 Q102 Ad T Care must be taken to ensure DLI01 6 4 e that the right polarity in the R106 m power input is respected pa 2 l Bi Ri 18 amp DO NOT Supply power when the Ad 8 BCR48PN a 2 Q101 0402 WTs 8 0 5 Battery is not connected 2 S TR2 507 363 E 0402 m SOT 323 8 2 9 NGA T R107 1 22K 2 3 DAZ l 2 3 naw x E ZA n lt Q RESET e e e gt LDO_ON_OFF KZ 5 717 2 4 2 9 3 6 3 7 4 6 5 28 5 20 5 8 TO HG GND Z 5 Wen R117 gt 47K aa Oo 5 amp 0402 ij GND PLI01 1984617PT1 5 2 3 5 H 2 1 yee m 2 3 8V M PL105 IN e 1215061 03F 3 1 1 2 5 40 IN 19 2 3 3 8V IN 1 2 Regulator 1215061 03F MH 2 3 PL104 0 WARNING Care must be taken to ensure D103 that the right polarity in the STPS140Z
6. 13 3 2 2 Thermal Design 15 3 2 3 Power Supply PCB layout 16 MEO DIM nem ee ANA AA 17 4 1 Antenna Requirements eren nre e neat o EX YR EY FXRERFREFEFREFEEKEFEERER 17 4 2 Antenna PCB lime Guidelines la etre tior RR ER RRRRRRXRRRRRRERRRRRR AIDA 18 4 3 Antenna installation 40 0 19 5 Serial Port 20 5 11 RS232 level translation ert rtr iter iren nt omite i EO EE E RR ER E E Ee SER 22 5 2 5V UART level 24 EROR 26 6 1 Microphone line Characteristic and requirements 26 6 2 General Design Rules GANANG 29 6 3 Microphone BIASING ET 29 6 3 1 Balanced Microphone 30 6 3 2 Unbalanced Microphone biasing aNG AN a ARUGA BAGA 31 6 4 Microphone sanan psa NAINA 32 6 4 1 Buffered Balanced AALAGA 32 6 4 2 Buffered Unbalanced Single Ended
7. 2 Pa MODIFY DATE PATH Archivio PCB cs1170 pm DESCRIPTION FILENAME _ 51170 j cs1 1 70 FILE GERBER Dai T 2 I2CBUS DUAL CAMERA 1 048 0 6 99 ANNOTATION FORM Project by Silkscreen side B A3 Drawn by Pasqualini Natascia 06 09 2005 Project SHEETN OF SHEETS DRAWING CODE Verif by 0276 2 2 51 1 70 5
8. 16 16v 300nF 0603 0603 HEY C801 46v 0603 PL803 6 3v 1815061 03F 0603 1 7 15 15 AH Ay 2 MUTE CONTROLLED sx a ALWAYS H3 _ END page 39 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 Some amplifier require a low impedance load at high frequency in order to avoid auto oscillation this can be made with a capacitor 100nF in series with a resistor 150 When designing your application remember to provide an adequate bypass capacitor to the amplifier and place it close to the power input pin of the IC keeping the traces as short as possible 7 4 Hands Free earphone low power design The same design considerations made for the handset are valid for the hands free earphone the only difference is that the external ear audio output level from the GE864 is 6dB lower than the internal one so the gain of the amplifier must be 6dB higher to provide the same audio level 7 5 Car Kit speakerphone design For the car kit speaker phone function the power output requirement is usually at least 4W therefore an amplifier is needed to boost the GE864 output The design of the amplifier shall comply with the following guidelines The input to the amplifier MUST be taken from the external audio path EAR EAR HF of the GE864 because of its echo canceller parameters suited to a car c
9. 18 Wa R520 100nF GND 100K S LL 17 AL 5 3 0V USB EB 77 n e BUSPWR PWRON3 e 10V H GND 5 amp 0402 374 R521 4 a la a dg 2 gt 5 9 of 0402 8 z 5 4 100 ON OFF jz a nj m 9 1 118 3 6 3 7 4 6 20 8 LI E 777 AD 8 mg lt KO noMount YES C502 5 gt e af x lt 100nF Ga oe a a gt 9 aa Po a gt 24 XSR ADBUSO 5 34 7 Q9 lov 02 93 x amp 403 5 3V30UT ADBUSI 23 SSCO_MTSR uz y E 2 4B ADBUS2 22 ssco_MRST g 8 i 2 4B GND ga USBDM ADBUS3 S 5 pa 5 ApBusa p2 a g 7 usBpp ApBUss H Eos 8 ADBUS6 H7 R506 R509 R514 s ovr 16 R522 R523 evum 20 Eg RSTOUT ADBUS7 15K 15K 15K 15K pak ie R526 5 4 x s RESET 5 5V USB LIT 5 5 5 5 noMount YES 22415 GND 0402 0402 0402 0402 ACBUSO XTIN FT2232 43 13 USB H B x XTIN ACBUSI U GND GND GND GND 5 75 ACBUS2 4 1 503 H 100 ON OFF 4 xrour suwua H 1 11B 3 6C 3 7B4 6E 2B 2D DEO 45V USB 48 EECS 9509 2 E e Zak 2 1 EESK FT2232L BpBuso fS pm 8 TRACE USB TET 9 C506 GENEE 2 LQFP48 BDBUSI 9 IX TRACE USB 3 U505 PUSR z
10. PROG USB 55 USBI lt gt TRACE SSC AN ST BDBUS2 HR TP532 O 3 ES TP533 O e GND BDBUS4 TP534 gt 5 55 t 33 Do 4 2 256 33 44 CJ USB 45V USB MODIFY BDBUS7 22 lug 1 RLUSB 32 R501 U501 DATE 18K 93LC56B_I SNG AUS Bcbuso 39 29 5 8 BCBUS1 0402 63 28 PATH home users area DESCRIPTION Ay 7 BCBUS2 ok a NG 27 2 412 04 3 6 BCBUS3 TP531 e 5 DI NC6 FILE NAME cs1139a 15 26 DAI TELECOM DO vss Dai Telecom Group ie Mod 067 rev 1 11 02 ANNOTATION FORM du o 2 9 OO 505 a 583 2 a PROJECT Furlan M 080705 USB lt gt PROG TRACE I2C SSC A3 lt 8 PROJECT SHEETN OF SHEETS DRAWING CODE USBO lt gt PROG 12 DRAWN Sera M 080709 ps 0276 5 5 302765 39 VERIFIED Nonis R 080705 27 7 111 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 Annex B Camera EVB schematics Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 57 of 60
11. 34 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 f UJDBSSKBE PAA 36 7 1 Speaker lines characteristics and 4 36 7 2 General Design THIS ANAN AABANG NANA B CERDO 37 7 2 1 Noise acne 38 1 3 Handset RR Kap ABAKA NIKKA 38 7 4 Hands Free earphone low power design 111 7 nnn 40 7 5 Car Kit Speakerphone design aNG ANGAS 40 E 42 Usinga GPIO as INPUT uman AA eni asas OX GER eua ei 42 8 2 Using a GPIO pad QUTPUT 42 8 3 Using the Alarm Output GPIO 06 ALARRM nennen nn 43 8 4 Using Buzzer Output GPIO 07 BUZZER 2 2 2 2 11 43 I ecc P cn 44 Camera ch racteristicS Tc P 44 9 1 1 Camera interface 44 9 1 2 Example usage script for camera 0 000 ns NAAN NAN NASAN NASAAN 47 10 Conformity Assessment Issues nn 48 11 SAFETY
12. AUDIO Switch a 9019915102410 s wows 25 878 4 gt El 5 WAZ e SHUTDOWN Sz 8 7 gt PL402 PL403 PL404 va BYPASS 1215061 05 1215061 05 1215061 05 3 A lt C403 C404 7 INE 9 e 1 1 1 100 100nF e e 01 10 53c T amp m uv S E STI 2 e EAR 5 E 0603 0603 og GND 3 o e a2 C408 g 3 100nF Ko e3 i xi lt 8 5 5 4 amp 16V e OF O MIC i Spi noMount YES d C414 596 5 GND GND luF 0603 0603 GND GND 217 777 GND OPTIONAL POWER AMPLIFIER 50401 1401 PJ25605 T2 2250 Z gt 83 3 5 Ex d 1402 EARPIECE 82150 7250 4 BLM21 y a BLM21 5 z 2 PJ25605 T2 s wA 07 C401 C402 C405 C406 C407 R403 9 22 10 22 InF 22K TP402 XIR 50V 16V 16V 50V 16V 5 0402 0402 0402 0402 0402 0402 77 588 7 GND GND GND GND GND ANI SND 437V E amp U402 102 LP2982AIM5X 3_0 NOPB m 5 ba rm Z V OUT VIN e 54 GND 2 405 i 4 C419 lt lt 22K BYPASS ON OFF 5 2 2uF gt pa GND mi 5 0402 C418 M Z 15 417 we lt 10uF XIR E 409 25v VE CONT A KOS XSR Dev 2 100 ON OFF dd T 11B 3 6C 3 7B 5 2B 5 2D 5 8C E
13. nnn nn nnns 49 12 Document Change LO ooo po 50 Annex A EVKZ schematics 51 Annex B Camera EVB schematics 57 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 1 Overview The aim of this document is the description of some hardware solutions useful for developing a product with the Telit GE864 module In this document all the basic functions of a mobile phone will be taken into account for each one of them a proper hardware solution will be suggested and eventually the wrong solutions and common errors to be avoided will be evidenced Obviously this document can not embrace the whole hardware solutions and products that may be designed The wrong solutions to be avoided shall be considered as mandatory while the suggested hardware configurations shall not be considered mandatory instead the information given shall be used as a guide and a starting point for properly developing your product with the Telit GE864 module For further hardware details that may not be explained in this document refer to the Telit GE864 Product Description document where all the hardware information is reported NOTICE EN The integration of the GE864 GSM GPRS cellular module within user application shall be done according to the design rules described in this manual IT L integrazione del modulo cellulare GSM GPRS GE864 all int
14. power input is respected 807123 7 a GND FUSE 1206 1 107 1984617 1 5_2 3 5 BATTERY LI ION l 3 7V Li Ion Nominal 720105 77 max voltage 4 2V Li Ion Oll 500123 LM2596S ADJ NOPB ENT suggested capacity 1000mAh MIN 5V EDU Lv vour Og e e al 2 5 4 7407727 ON OFF FBACK m ioi C101 02 C103 104 cu Cu Sio C106 C107 R114 C108 A H7 cl STPS3L60U Nn mr ir gu P 4 STPS3L60U 330uF 3300F 20K MEL WARNING AN GND 986 50v 50 sov 50v pik 63V 63V 1 16V When using battery care must be lt 0603 0603 0603 16X16 5 NR CONT E CONT E 0603 0402 N o taken to ensure that the right z 21 polarity is respected 777 Z 77 Ei GND GND GND z a GND GND GND GND lt Eas Ea 5 gt 50101 ERE AN RAPC712X e a 8 8 R115 1 2 5 8 E 9 POWER LOK ER JACK se m e KAPG 0603 MODIFY 77 7 GND take DATE PATH home users area DESCRIPTION FILE NAME cs1139a cir DAITELECOM Dai Telecom Group OT101 OT102 OT103 Mod 067 rev 1 11 02 ANNOTATION FORM n EN PROJECT Furlan M 080705 POWER REGULATOR BATTERY CHARGE A 3 SHEET OF SHEETS DRAWING CODE DRAWN Serdi M 080705 VERIFIED Nonis R 080705 0276 1 5 30276SE11139A
15. 560 99 INPUT Usi icd C205 1202 50202 UG 3 OUTPUT ph 5 van mE C210 2 sour SHINY SENSI m m Ceo C206 4 1 0203 10 DRESE ee STRS140z GONT D Rana fief 7 GND 2 L 205 SMark 2 76 SND Bana Bay B 1 BnF 500123 CONT E yn 50 BNO CAI d BAD GND GND fv Se Banga CRID GC864 Hardware User Guide 10300694 Rev 3 07 02 06 3 2 1 3 Battery Source Power Supply Design Guidelines e The desired nominal output for the power supply is 3 8V and the maximum voltage allowed is 4 2V hence a single 3 7V Li lon cell battery type is suited for supplying the power to the Telit GE864 module The three cells Ni Cd or Ni MH 3 6 V Nom battery types or 4V PB types MUST NOT BE USED DIRECTLY since their maximum voltage can rise over the absolute maximum voltage for the GE864 and damage it NOTE DON T USE any Ni Cd Ni MH and Pb battery types directly connected with GE864 Their use can lead to overvoltage on the GE864 and damage it USE ONLY Li lon battery types e A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks a 100 F tantalum capacitor is usually suited e Make sure the low ESR capacitor usually a tantalum one is rated at le
16. e 25 24 GND O4 9 j 25 gt e GND 27 26 GND Le GND 2 a e st 2 GND 8 3 3 E 2 gt EAR_HF qn 24 GND EAR a 5 2 TO MT 80201 m EAR gt EAR_HF FMS0062 2001 0 d EAR gt EAR MT e SIMIO 5 3 SIMCLK 5 SIMCLK 4 11B D MIC HF SIM SIMRST e SIMRST KZ 35 4 11B SIMVCC 3 wn lt ic mts B e SIMVCC lt 36 35 N SIMIN MIC MT 2 MIC MT 8 7 l e 38 49B SIMIN 37 GND 6 1 201 202 C203 C204 le e 39 33pF 33pF 33pF 33pF 38 GND OF F3 coe cog GND 40 50 50 50v 50 39 GND OF OND 0402 0402 0402 0402 GND lg GND amp 77 GND GND GND GND 5 EN Ed gt 5 aS Ae Zag lt i EZ sm z RESET BUTTON Donor R201 SW201 MODIFY 330 5 2 5 gt RESET f 1 DATE 0603 4 SKHHAL 2 1 9B 9C 8 DESCRIPTION a YELLOW STAT LED M676 gt ONBUTTON PATH home users area YELLOW a Noy 777 LY M676 Q281 26 85 FILE NAME cs1139a cir DAI TELECOM 2 DL201 Telecom Group 7 Mod 067 1 11 02 ANNOTATION FORM PROJECT Furlan M 080705 INTERFACE CONNECTORS A 3 L lt STAT LED 9C Serdi M PROJECT SHEET N OF SHEETS DRA
17. whose absolute maximum output current is 100mA Pull up resistors can be connected to the VAUX pad provided that the pulled up lines are GE864 input lines connected to open collector outputs in order to avoid latch up problems on the GE864 Care must be taken to avoid latch up on the GE864 and the use of this output line to power electronic devices shall be considered with care especially for devices that generate spikes and noise such as level translators digital ICs or microcontroller failure in any of these condition can severely compromise the GE864 functionality NOTE The input lines working at 2 8VCMOS can be pulled up with 47 resistors that can be connected directly to the VAUX line NO disturbing devices should be powered with the VAUX line otherwise the module functionality may be compromised um Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 25 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 6 Microphone The microphone circuitry is the more noise sensitive and its design and layout must be done with particular care 6 1 Microphone line Characteristic and requirements The Telit GE864 provides two audio paths for the microphone and the earpiece the internal and the external audio paths Only one of the two paths can be active at a time and it is selectable by hardware line AXE or by AT command The audio chara
18. 1 1 1 1 1 0904 1 TDABHSA435F hM1i 2 ET m 1 mi i YCE NG S E 1 ejje T JEAR HF4 pi ago TO SPEAKER 41 The 18 4 BOHM Sy T 5 1 a in i lt JEP HF gl i i 1 legoi 91 anon 6 i S 1 m 1 PLg01 mi 1 i C9140 rapa 1 ls BNO sour ligone p e HUTE CONTAOLLED ila ALWAYS DN i 1 LUNT E Deos i i END od AMPLI POWER CONTROL 1 1 1 1 r 68 _ Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 41 of 60 m s GC864 Hardware User Guide 10300694 Rev 3 07 02 06 8 General Purpose The general purpose pads can be configured to act in three different ways input output alternate function internally controlled Input pads can only be read and report the digital value high or low present on the pad at the read time output pads can only be written or queried and set the value of the pad output an alternate function pad is internally controlled by the GE864 firmware and acts depending on the function implemented Not all GPIO pads support all these three modes GPIO 06 ALARM supports all three modes and can be input output alarm output Alternate function GPIO 07 B
19. Guide 10300694 Rev 3 07 02 06 4 Antenna The antenna connection and board layout design are the most important part in the full product design and they strongly reflect on the product overall performances hence read carefully and follow the requirements and the guidelines for a proper design 41 Antenna Requirements As suggested on the Product Description the antenna for a GE864 device shall fulfill the following requirements ANTENNA REQUIREMENTS Frequency range Dual Band GSM DCS frequency range or Standard Tri Band GSM DCS PCS frequency range if used for all three bands Bandwidth 80 MHz in GSM 8 170 MHz in DCS 8 140 MHz PCS band Gain Gain lt Impedance 50 ohm Input power 5 2 W peak power VSWR absolute lt lt 10 1 max VSWR lt lt 2 1 recommended When using the Telit GE864 since there s no antenna connector on the module the antenna must be connected to the GE864 through the PCB with the antenna pad In the case that the antenna is not directly developed on the same PCB hence directly connected at the antenna pad of the GE864 then a PCB line is needed in order to connect with it or with its connector GC864 Hardware User Guide 10300694 Rev 3 07 02 06 This line of transmission shall fulfil the following requirements ANTENNA LINE ON PCB REQUIREMENTS Impedance 50 ohm Max Attenuation 0 3 dB No coupling with
20. power level at which the device is requested to transmit by the network The average current consumption hence varies significantly TIP The thermal design for the Power supply should be made keeping a average consumption at the max transmitting level during calls of 500mA rms Considering the very low current during idle especially if Power Saving function is enabled it is possible to consider from the thermal point of view that the device absorbs current significantly only during calls If we assume that the device stays into transmission for short periods of time let s say few minutes and then remains for a quite long time in idle let s say one hour then the power supply has always the time to cool down between the calls and the heat sink could be smaller than the calculated one for 500mA maximum RMS current or even could be the simple chip package no heat sink Moreover in the average network conditions the device is requested to transmit at a lower power level than the maximum and hence the current consumption will be less than the 500mA being usually around 150mA For these reasons the thermal design is rarely a concern and the simple ground plane where the power supply chip is placed can be enough to ensure a good thermal condition and avoid overheating For the heat generated by the GE864 you can consider it to be during transmission 1W max during CSD VOICE calls and 2W max during class10 GPRS upload This generated he
21. the gain of the not inverting buffer is 1 5 4dB While the gain of the inverting buffer is given by the formula R711 Gain R708 As shown in the balanced buffered mic the gain adjustments can be done by changing R719 R720 and R708 R711 and as a consequence the capacitors C726 and C727 m Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 34 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 The bandwidth 3dB is given by the approximated formula considering C725 gt gt C726 1 1 freq 2 2 719 726 2 711 727 The buffer bandwidth at 3dB shall be 8kHz Note that the biasing of the operational amplifier is given for the inverting amplifier by the series divider R714 R715 The 100nF capacitor C719 is needed to filter the noise that could be coupled to that divider For the not inverting operational the biasing is given by a different divider R715 R717 with the capacitor C720 and through a series resistor R718 of 470KO For example Let s assume you have a microphone with these characteristics sensitivity 45 ABy mspa and you want to use it in the external mic audio path With the mic having nominal sensitivity 45dB pa at the normal spoken conditions 4 7dB pa but at 50 cm from the mouth of the talker an additional 20 dB loss shall be considered At that acoustic pressure the volta
22. tsm Tsour O 2 GND un 18 DSR lt TU aq run 5 a O RTS USB RS232 Switch lt 20 rour kan 1 4 to lets ag 184 aq 24 O OB xb P Dp 2 2 TIN GND aN PE 59 zd o ae Zu Sz KOS Ho a 58 2 MODIFY DATE PATH home users area DESCRIPTION FILE NAME cs1139a cir DAI TELECOM Dai Telecom Group Mod 067 rev 1 11 02 ANNOTATION FORM PROJECT Furlan M 080705 UART A 3 DRAWN Sia 080705 PROJECT SHEET N OF SHEETS DRAWING CODE erdi M VERIFIED Nonis R 080705 0276 3 5 30276SE11139A 2 3 4 5 6 9 10 11 ME Ze noMount YES 3 E 5 Zo og e e noMount YES noMount YES IN 0401 n JP403 C LM4862MX NOPB t a9 PLAOI
23. uv E 0402 MODIFY 117 DATE DESCRIPTION PATH home users area LE ata I2CBUS DUAL CAMERA FERNAME cs1170 cir LL 7 DAI TELECOM Dai Telecom Group Mod 067 rev 1 11 02 ANNOTATION men PROJECT Furlan M A 3 PROJECT N OF SHEETS DRAWING CODE iu 1060905 S Draw vitm 0276 1 1 30276SE11170 TUTTI I DIRITTI RISERVATI RIPRODUZIONE E DIVULGAZIONE ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE VIETATE FORBIDDEN CI RIN 50106 BAR CODE 50104 50105 ae MODIFY DATE PATH Archivio_PCB cs1170 DESCRIPTION FILENAME _ 1170 j cs1 1 70 FILE GERBER Dai T 2 I2CBUS DUAL CAMERA 1 048 0 6 99 ANNOTATION FORM Project by Silkscreen side A A3 Drawn by Pasqualini Natascia 06 09 2005 Project OF SHEETS DRAWING CODE Vert by 0276 1 2 CS1170 SM 50101 NI NI TUTTI I DIRITTI RISERVATI RIPRODUZIONE E DIVULGAZIONE VIETATE ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE FORBIDDEN
24. 0 8000 Hz 3 850 MV ims 10 mW 30 mW 2dB 10 DC bridged gt 16 15 1kHz 15 150 8000 Hz 3 425 MV ms 2 5 mW 7 5 mw 2 dB 10 i Cs 4 Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 36 of 60 The EVK2 1 2 audio output characteristics internal external ear single ended GC864 Hardware User Guide 10300694 Rev 3 07 02 06 e line coupling AC line type single ended referred to GND Speaker impedance operating conditions 280 minimum load impedance 8Q e signal bandwidth 150 8000 Hz 3 dB maximum output 800 mV maximum power output 80 mW 80 e THD N 1 80mW internal external ear bridged e line coupling DC e line type bridged not referred to GND e speaker impedance operating conditions 280 minimum load impedance 8Q e signal bandwidth 150 8000 Hz 3 dB e maximum output 1 6 Vims maximum power output 320 mW 080 e THD N 1 330mW high power external ear e line coupling DC e line type bridged not referred to GND e speaker impedance operating conditions 24Q minimum load impedance 4Q e signal bandwidth 150 8000 Hz 3 dB e maximum power output 6W e THD N 10 6W 7 2 General Design rules There are several configurations for the audio output path but the various design requirements can be grouped into three diff
25. 33v B sU i T Tr GND a UBD Wm oe 7 SIETE Cx d Sus 2 Ou mm EE 11 4 Le conned eee mi 0 Go n LO HE This circuit has gain of 15 times 24 dB and is therefore suited for the internal mic input having microphone with a sensitivity close to the suggested 45 AByrms pa if the used microphone has different sensitivity or if the buffer is connected to the external mic input then a gain adjustment shall be done by changing resistors R604 R605 and R606 R607 and as a consequence the capacitors C636 and C637 to maintain the bandwidth 150 8000 3dB The buffer gain is given by the formula _ 604 _ R606 R605 R607 Gain Reproduction forbidden without Telit Communications S p A written authorization All Right reserved 32 of 60 GC864 Hardware User Guide 1vv0300694 3 07 02 06 The C636 and C637 capacitors are placed in order to cut off the gain at higher frequencies than the transmitted GSM band the cutoff frequency 3dB should be 8 kHz in order to have 1dB at 4kHz The cutoff frequency is given by the formula 1 1 2 R604 C637 27 R606 C636 freq Hz For example Let s assume you have a microphone with these characteristics sensitivity 45 dBymspa and you want to use it in the internal mic audio path With the mic having nominal sen
26. 6 riour RIIN 2 a GND 20 9 25 lt lt lt R20UT R2IN gt 5 24 BO rour H KO 13 EN 15 14 lt MBAUD SHDN D 9 2 8 5 2 230v e 5 77 JP303 Po U301 E GND LP2982AIMSX 3 0 NOPB m SO301 P EE CD81VISSAAC evn e e p PL301 PL302 PL303 2 1215061 10 1215061 10 1215061 10 2 26 21 C301 3 4 E n gt IX TRACE USB 4 1 a 1 le 1 1 ON OFF BYPASS 5 ma 4 3L jaa ang a _ 2 o 15 Kat AUNG 5 2 35 2 2 gt aN R301 R302 R303 R305 8306 Uc 5 wb aL D sic TRACE RX TRACE UM ax pex pex ex 0 2 DOPROCUSB ag tlg 15 C304 5 5 5 5 5 Pc aoe Lo o 3 2 5 5 ASCO le 4 Xm 0402 0402 0402 002 0402 i 5 HE c lt e PROG ous 5 5 on CONT A E 7L Lo Dp 2 2 3C 68 3 RS e d coros Ng lo 10303 GND 8C KO 2 3C 7 E LDO_ON_OFF 5 7 9L e C108 DTR 1 498 AH 1 11B 7B 4 6E 5 2B 5 2D 5 8C MAX3237CAI 2 3C n SSOP 28 e CI09DCD o go ile 2 e O DCD 2 3B 9 9 23 2 15 O gt 23 ran O O RXD 23 3 e 9 corso ug i e pi gt 22 sin 07 gt to O O EL 2 3C 9 2 e 9 ran tour O DTR O USB B RS232 e
27. 7 2472 Ball Signal Pin Signal C6 CAM SCL IIC SCL O 12 bus serial clock 1 SCLK GND Ground 2 O 2 8V Regulator enable 3 AVDD28 controlled by PWR ON C9 TGPIO 09 CAM RS O Camera Reset 4 RESET_N F8 Clock 5 IN GND Ground 6 DGND 7 DOUT 0 8 DOUT 1 9 DOUT 2 10 DOUT 3 11 DOUT 4 12 DOUT 5 13 DOUT 6 7 sd bi am 2 Bagac D Reproduction forbidden without Telit Communications S p A written authorization All Right reserved 44 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 nce 14 DOUT 7 lo 15 DOUT 8 16 VCLKOUT O 17 VALIDH O n c 18 VALIDV O VCC_MAIN_CAM O External 2 8V Regulator enable 19 DVDD28 controlled by CAM PWR ON D7 CAM SDA IIC SDA I O T bus serial data 20 SDIN GND Ground 21 PS1 K11 TGPIO 08 CAM ON power type selector 22 PS2 I GND Ground 23 SHIELD Flash Enable 24 LED CTRL O Filter the AVDD28 Use a Buffer between module clk out MON1 CAM and camera clk in
28. CLK IN lt Not connected Camera Socket Connector Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 45 of 60 Telit GC864 Hardware User Guide 1vv0300694 Rev 3 07 02 06 EVB for Transchip camera support In order to interface the Telit GE864 module with a CMOS camera Telit has developed an evaluation board see Annex B The EVK2 see Annex A allow connecting all Telit modules through 2 connectors of 40 pins each The I2CBUS CAMERA board is plugged in the 2 connectors of 30 pins each the module board CAMERA MODULE BOARD MAIN BOARD EVAZ 1 Lm Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 46 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 9 1 2 Example usage script for camera Camera setting shown here are the defaults ones gt AT CAMSEL 0 camera selection 0 auto 2 transchip OK gt AT CMODE 0 camera mode 0 day 1 night OK gt ATHCAMQUA 0 camera quality O low 1 medieum 2 high OK gt AT CAMRES 0 camera resolution 0 1 QVGA 2 QQVGA OK gt AT CAMCOL 0 camera color 0 color 1 grayscale OK gt AT HCAMZOOM 0 Camera zoom 0 x1 1 x2 2 x4 OK gt 0 camera t
29. Communications S p A written authorization All Right reserved page 23 of 60 GC864 Hardware User Guide 1vv0300694 Rev 3 07 02 06 5 2 5V UART level translation If the OEM application uses a microcontroller with a serial port UART that works at a voltage different from 2 8 3V then a circuitry has to be provided to adapt the different levels of the two sets of signals As for the RS232 translation there are a multitude of single chip translators but since the translation requires very few components then also a discrete design can be suited For example a possible inexpensive translator circuit for a 5V driver can be BCR22PN WPS 501 363 3 a 4 2989 2 HARDWARE 77 R7 C 11 0 47K CR10 and for a 5V receiver C103 Tx0 5y ave PWRETL 4 5 G1 WPS 501 363 5 C103 TxB 2 a page 24 of 60 Telit GC864 Hardware User Guide 1vv0300694 Rev 3 07 02 06 NOTE The UART input line TXD rx uart of the GE864 is NOT internally pulled up with a resistor so there may be the need to place an external 47 pull up resistor either the DTR dtr uart and RTS rts uart input lines are not pulled up internally so an external pull up resistor of 47KQ may be required A power source of the internal interface voltage corresponding to the 2 8VCMOS high level is available at the VAUX pad
30. Guide 10300694 Rev 3 07 02 06 2 2 Turning OFF the GE864 The turning off of the device can be done in three ways e by software command see GE864 Software User Guide e by hardware shutdown When the device is shut down by software command by hardware shutdown it issues to the network a detach request that informs the network that the device will not be reachable any more 2 2 1 Hardware shutdown To turn OFF the GE864 the pad ON must be tied low for at least 1 second and then released The same circuitry and timing for the power on shall be used The device shuts down after the release of the ON pad TIP To check if the device has powered off the hardware line PWRCTL should be monitored When PWRCTL goes low the device has powered off 2 3 Hardware Unconditional Reboot To unconditionally Reboot the GE864 the pad RESET must be tied low for at least 200 milliseconds and then released The maximum current that can be drained from the ON pad is 0 15 mA A simple circuit to do it is RESET Unconditional Reboot impulse GND NOTE don t use any pull up resistor on the RESET line nor any totem pole digital output Using pull up resistor may bring to latch up problems on the GE864 power regulator and improper functioning of the module The line RESET must be connected only in open collector configuration EZ pg In i da i m E 4 Li ES GC864 H
31. HL e lel wireless solutions GE864 Hardware User Guide GE864 PY GE864 QUAD 1vv0300694 Rev 3 07 02 06 X L 4 2 7 d Making machines talk GC864 Hardware User Guide 10300694 Rev 3 07 02 06 Contents 1 4 2 Hardware 5 2 1 Turning the 864 um KANG GAN KNA ALAS 5 2 2 Turning OFF the i iiicicciiescievsveiccesivedsievscverscsvvssvsesdaveuveeducesdesdsdenscsivdueleessdeess erseriedeeinedss 7 2 2 1 Hardware shutdown ak 7 2 3 Hardware Unconditional Reboot sess nnne nnn nnn nnns 7 3 POW leer RE ee 9 3 1 Power Supply 9 3 2 General Design Rules 10 3 2 1 Electrical design 10 3 2 1 1 5V input Source Power Supply Design Guidelines 10 3 2 1 2 12V input Source Power Supply Design Guidelines 12 3 2 1 3 Battery Source Power Supply Design 13 3 2 1 4 Battery Charge control Circuitry Design
32. Reproduction forbidden without Telit Communications S p A written authorization All Right reserved 22 of 60 GC864 Hardware User Guide 1vv0300694 Rev 3 07 02 06 An example of level translation circuitry of this kind is Ud 13v 207 550P 24 mu m rc ox oO 10 10 vee 2 NG alo O o 12 11 4 C1 v 13 e r a ac m x u oy 42 c 0 B 14 15 Cen NG oa m BESO 87 9 77 7 2 GND O T1 IN gt 6232 5 3 tx uart O 4 T2 1N T2 QUT CO TX RS23 18 1 dsr uart 2 34 13 IN TAS_OUT gt DSA_AS292 19 24 cts_uart bam 4 14 1N T4 QUT CTS R5232 21 20 ri uart 5 4 IN T5_OUT RI HS239 5 4 lt 1 BILIN lt _ 5292 23 rts uart C R2 0UT A2 INET O R18 R8232 17 16 lt P3 DUT ASIN DTR RS238 GND B B END the RS232 serial port lines are usually connected to a DB9 connector with the following layout DCD RS232 DSR RS232 a 2 TX RS232 S ro RIS PSses2 e RX RS232 CTS_AS232 O DTR_AS2 32 lt __ Ola RI RS232 O pa Al pa E lud Reproduction forbidden without Telit
33. TP101 AD ot TP102 HO 24 ILS E lo O TP103 10 NA a bouts 104 O 11 bouts O TP105 p FO 12 ID m O TP106 lt gt 5s 9 13 1 Pola O TP107 29 9 ES 29 DONT gat O TP108 RE O Dours aas 36 LL OF O TP109 4 il 16 Ha 17 O O 18 VALIDY O E O TP112 19 mo DVDD28 2 JPIO8 SDIN 20 WO 21 o PSI 3 3 JPTOS 22 Ps2 P Add i 9B pm o YET INTERFACE CONNECTORS 24 s un cmi C 50104 LA 4773540102470 1 50106 C110 4773540103470 ET 2 63V CAM 0603 O JP121 LAHI 477 a E as s8 ja ERN 3 1102 LP2982AIMSX 2 8 NOPB 9 5 R108 7 TransChip TC5747MF24L 24pin EI 7 o ka haie gt 4 3 E 0 sov 63V vans ON OFF 0402 0402 0603 3B 77 TT LISA C106 C104 C105 MAISA ki pi vec man cat 8 ws a SNHLVCIONDCKR Jet LA R109 1 ET 3 2 25 E 25 0 5 2 Ng 120 0402 0402 HS U101 i NE gae 77 TI MTI Pp E 7 i lt C S 5 7 4 d ELT ak ori ER s 5 EG g 53 ce 7 az al 6 C12 5 E N vwe 010 BB wm
34. UZZER supports all three modes and can be input output buzzer output Alternate function 8 1 Using a GPIO pad as INPUT The GPIO pads when used as inputs can be connected to a digital output of another device and report its status provided this device has interface levels compatible with the 2 8V CMOS levels of the GPIO If the digital output of the device to be connected with the GPIO input pad has interface levels different from the 2 8V CMOS then it can be connected to GPIO1 or can be buffered with an open collector transistor provided a 47KQ pull up resistor is connected as seen in the paragraph 5 2 5V UART Level translation 8 2 Using a GPIO pad as OUTPUT The GPIO pads when used as outputs can drive 2 8V CMOS digital devices or compatible hardware When set as outputs the pads have a push pull output and therefore the pull up resistor may be omitted GC864 Hardware User Guide 10300694 Rev 3 07 02 06 8 3 Using the Alarm Output GPIO 06 ALARM The GPIO 06 ALARM pad when configured as Alarm Output is controlled by the GE864 module and will rise when the alarm starts and fall after the issue of a dedicated AT command This output can be used to power up the GE864 controlling microcontroller or application at the alarm time giving you the possibility to program a timely system wake up to achieve some periodic actions and completely turn off either the application and the GE864 during sleep periods drammat
35. WING CODE DRAWN 080705 1 2 3 6 7 8 9 10 11 43 7V a ap 302 JP302 LP2982AIMSX 3 0 NOPB O E 1 5 e V_IN 2 owp 26 202 3_lon orr Bypass 4 3 m 1 XSRL Uses 28 27 O 63V 120A gt V 0603 MAOSA C305 25 C306 18304 Per XIR 10uF 25V lov 1 N NE nb CONT A s v 3 fen 10304 GND LDO ON OFF 5 1 11 6 4 6 5 2 5 20 5 8 MAX3237CAI GN 2 SSOP 28 5 O 23 6 gt T2IN T20UT x 22 7 e 4 T3OUT o 19 10 a T4OUT Q ol sour D2 SH 4 TSOUT KR 3 RIOUTB 2 77 21
36. abin use The amplifier shall have a gain of 30 40 times 29 32 dB to provide the desired output power of 5 10W with the signal from the GE864 external audio output lines EAR e If the amplifier has a fixed gain then it can be adjusted to the desired value by reducing the input signal with a resistor divider network e The amplifier shall have a mute control to be used while not in conversation This results in two benefits eliminating the background noise when not in conversation and saving power e The power to the amplifier should be decoupled as much as possible from the GE864 power supply by either keeping separate wires and placing bypass capacitors of adequate value close to the amplifier power input pads e The biasing voltage of the amplifier shall be stabilised with a low ESR e g a tantalum capacitor of adequate value NOTE The GE864 audio path connected to the car kit hands free amplifier MUST be the external one EAR_HF otherwise the echo cancellation will not be done due to the difference in the echo canceller characteristics of the GE864 internal audio path from the external audio path GC864 Hardware User Guide 10300694 Rev 3 07 02 06 An example of car kit amplifier schematic can be HIGH POWER EXT EAR AMPLIFIER 6w t
37. ame cautions have to be taken for the SIM checking carefully the instruction for its use Do not insert or remove the SIM when the product is in power saving mode The system integrator is responsible of the functioning of the final product therefore care has to be taken to the external components of the module as well as of any project or installation issue because the risk of disturbing the GSM network or external devices or having impact on the security Should there be any doubt please refer to the technical documentation and the regulations in force Every module has to be equipped with a proper antenna with specific characteristics The antenna has to be installed with care in order to avoid any interference with other electronic devices and has to guarantee a minimum distance from the body 20 In case of this requirement cannot be satisfied the system integrator has to assess the final product against the SAR regulation The European Community provides some Directives for the electronic equipments introduced on the market All the relevant information s are available on the European Community website http europa eu int comm enterprise rtte dir99 5 htm The text of the Directive 99 05 regarding telecommunication equipments is available while the applicable Directives Low Voltage and EMC are available at http europa eu int comm enterprise electr equipment index en htm page 49 of 60 GC864 H
38. anced Microphone biasing The balanced microphone bias voltage should be obtained from a dedicated voltage regulator in order to eliminate the noise present on the power lines This regulator can be the same for all the audio paths The microphone should be supplied from a capacitor multiply circuit For example a circuit for the balanced microphone biasing can be 3 3V MIC MIC Biasing Regulator Capacity multiply circuit 1 i C1 i 1 1 1 1 i 1 k 1 1 i 1 LI 1 1 1 1 1 1 1 4 1 1 1 1 1 1 i Electret micropnone 1 Eo ET PU MICH Cj i 1 1 1 NM MIC Buffer amplifier i o 1 1 1 i 1 1 1 CJ 1 0402 O NOTE In the balanced application the resistors R2 and R3 must have the same value to keep the circuit balanced NOTE The cable to the microphone should not be shielded instead a twisted pair cable shall be used NOTE The microphone sensitivity changes with the value of R2 and R3 Usually the microphones are characterized with 2kQ biasing resistance so try to keep the sum of R2 and R3 around 2kQ Refer to your microphone manufacturer for the mic characteristics Reproduction forbidden without Telit Communications S p A written authorization A
39. and OEM hardware Several configurations can be designed for the serial port on the OEM hardware but the most common are 5232 PC com port microcontroller UART 2 8V 3V Universal Asynchronous Receive Transmit microcontroller UART 5V or other voltages different from 2 8V Depending from the type of serial port on the OEM hardware a level translator circuit may be needed to make the system work The only configuration that doesn t need a level translation is the 2 8V UART The serial port on the GE864 is a 2 8V UART with all the 7 RS232 signals It differs from the PC RS232 in the signal polarity RS232 is reversed and levels The levels for the GE864 UART are the CMOS levels Absolute in Ratings Not Functional Parameter Parameter GU level on any LM 3V 3 75 digital pad when Input voltage on 0 3V T3 V analog pads when on Operating Range Interface levels 2 8V CMOS Level Level Mn Input Pigh Tevel 24 Reproduction forbidden without Telit Communications S p A written authorization All Right reserved 20 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 The signals of the GE864 serial port are Eba Pin Nr Number carrier presence tx uart rx uart dtr uart READY condition 45 48 50 56 ola dsr uart module is ready rts uart Hardware flow control LT cts_uart Hardware flow control CAITIE CAT ri uart incom
40. ardware User Guide 10300694 Rev 3 07 02 06 TIP The unconditional hardware reboot should be always implemented on the boards and p software should use it as an emergency exit procedure For example 1 Let s assume you need to drive the RESET pad with a totem pole output of a 3 5 V microcontroller UP OUT2 RESET LI 3 na gt BCS47BW 507 523 1F5 Tor m AFK O Wo 28 0402 j F j WAL i 6 ag Reproduction forbidden without Communications S p A written authorization All Right reserved page 8 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 3 Power Supply The power supply circuitry and board layout are a very important part in the full product design and they strongly reflect on the product overall performances hence read carefully the requirements and the guidelines that will follow for a proper design 3 1 Power Supply Requirements The GE864 power requirements are e Nominal Supply Voltage 3 8V e Max Supply Voltage 4 2V e Supply voltage range 34V 42V e Max Peak current consumption impulsive 1 9A e Max Average current consumption during GPRS transmission rms 500 mA e Max Average current consumption during VOICE CSD transmission rms 270 mA e Average current during Power Saving z4mA e Average current during idle P
41. ardware User Guide 10300694 Rev 3 07 02 06 12 Document Change Log Revision ISSUE 0 ISSUE 1 ISSUE 2 ISSUE 3 Date 12 06 06 22 11 05 19 12 05 07 02 06 Changes Release First ISSUE 0 Added notice on page 4 Added Paragr 10 Conformity Assessment Issues Added products order codes table Added Disclaimer Added Safety Recommandations Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 50 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 Annex A EVK2 schematics Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 51 of 60
42. ast 10V protection diode should be inserted close to the power input in order to save the GE864 from power polarity inversion Otherwise the battery connector should be done in a way to avoid polarity inversions when connecting the battery e The battery capacity must be at least 500mAh in order to withstand the current peaks of 2A the suggested capacity is from 500mAh to 1000mAh 3 2 1 4 Battery Charge control Circuitry Design Guidelines The charging process for Li lon Batteries can be divided into 4 phases Qualification and trickle charging e Fast charge 1 constant current Final charge constant voltage or pulsed charging e Maintenance charge The qualification process consists in a battery voltage measure indicating roughly its charge status If the battery is deeply discharged that means its voltage is lower than the trickle charging threshold then the charge must start slowly possibly with a current limited pre charging process where the current is kept very low with respect to the fast charge value the trickle charging During the trickle charging the voltage across the battery terminals rises when it reaches the fast charge threshold level the charging process goes into fast charge phase During the fast charge phase the process proceeds with a current limited charging this current limit depends on the required time for the complete charge and from the battery pack capacity During this phase the voltage across t
43. at will be mostly conducted to the ground plane under the GE864 you must ensure that your application can dissipate it GC864 Hardware User Guide 10300694 Rev 3 07 02 06 3 2 3 Power Supply PCB layout Guidelines As seen on the electrical design guidelines the power supply shall have a low ESR capacitor on the output to cut the current peaks and a protection diode on the input to protect the supply from spikes and polarity inversion The placement of these components is crucial for the correct working of the circuitry A misplaced component can be useless or can even decrease the power supply performances The Bypass low ESR capacitor must be placed close to the Telit GE864 power input pads or in the case the power supply is a switching type it can be placed close to the inductor to cut the ripple provided the PCB trace from the capacitor to the GE864 is wide enough to ensure a dropless connection even during the 2A current peaks The protection diode must be placed close to the input connector where the power source is drained The PCB traces from the input connector to the power regulator IC must be wide enough to ensure no voltage drops occur when the 2A current peaks are absorbed Note that this is not made in order to save power loss but especially to avoid the voltage drops on the power line at the current peaks frequency of 216 Hz that will reflect on all the components connected to that supply introducing the nois
44. charged and its voltage drops below a certain threshold GE864 internal charger does it As you can see the charging process is not a trivial task to be done moreover all these operations should start only if battery temperature is inside a charging range usually 5 C 45 The GE864 measures the temperature of its internal component in order to satisfy this last requirement it s not exactly the same as the battery temperature but in common application the two temperature should not differ too much and the charging temperature range should be guaranteed NOTE For all the threshold voltages inside the GE864 all threshold are fixed in order to maximize Li lon battery performances and do not need to be changed NOTE In this application the battery charger input current must be limited to less than 400mA This can be done by using a current limited wall adapter as the power source page 14 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 3 2 2 Thermal Design Guidelines The thermal design for the power supply heat sink should be done with the following specifications e Average current consumption during transmission PWR level max rms 500mA e Average current consumption during transmission PWR level min rms 100mA e Average current during Power Saving 4mA Average current during idle Power Saving disabled 19mA NOTE The average consumption during transmissions depends on the
45. cteristics of the two paths are slightly different and this should be kept in mind when designing The internal audio path should be used for handset function while the external audio path is suited for hands free function car kit Both microphone paths from the Telit GE864 are balanced and the OEM circuitry should be designed balanced to reduce the common mode noise typically generated on the ground plane however for particular OEM application needs also an unbalanced circuitry can be used The microphone input lines characteristics are internal microphone path e line coupling AC 100nF cond e line type balanced e differential input resistance 25 line nominal sensitivity 50 MV ms e max input voltage 360 MV ims e microphone nominal sensitivity analog gain suggested 45 ABy msipa 24dB e echo canceller type handset external microphone path e line coupling AC 100nF cond e line type balanced e differential input resistance 25 e line nominal sensitivity 3 MV ms e max input voltage 22 MV ms e microphone nominal sensitivity analog gain suggested 45 10dB e echo canceller type car kit hands free TIP Due to the difference in the echo canceller type the internal audio path is suited for handset applications while the external audio path is suited for car kit hands free The headset applications should be made by using the external audio path but DISABLING the echo canceller by softwa
46. e floor at the burst base frequency For this reason while a voltage drop of 300 400 mV may be acceptable from the power loss point of view the same voltage drop may not be acceptable from the noise point of view If your application doesn t have audio interface but only uses the data feature of the Telit GE864 then this noise is not so disturbing and power supply layout design can be more forgiving The PCB traces to the GE864 and the Bypass capacitor must be wide enough to ensure no significant voltage drops occur when the 2A current peaks are absorbed This is for the same reason as previous point Try to keep this trace as short as possible The PCB traces connecting the Switching output to the inductor and the switching diode must be kept as short as possible by placing the inductor and the diode very close to the power switching IC only for switching power supply This is done in order to reduce the radiated field noise at the switching frequency 100 500 kHz usually The use of a good common ground plane is suggested The placement of the power supply on the board should be done in such a way to guarantee that the high current return paths in the ground plane are not overlapped to any noise sensitive circuitry as the microphone amplifier buffer or earphone amplifier The power supply input cables should be kept separate from noise sensitive lines such as microphone earphone cables page 16 of 60 GC864 Hardware User
47. e microphone and the earpiece the internal and the external audio paths Only one of the two paths can be active at a time and it is selectable by hardware line AXE or by AT command The audio characteristics of the two paths are slightly different and this should be kept in mind when designing your application The internal audio path should be used for handset function while the external audio path is suited for hands free function car kit Both speaker outputs from the Telit GE864 are bridged type and the OEM circuitry shall be designed bridged to reduce the common mode noise typically generated on the ground plane and to get the maximum power output from the device however for particular OEM application needs also a single ended circuitry can be designed The GE864 speaker output lines characteristics are internal speaker path EAR EAR line coupling line type speaker impedance operating conditions minimum load impedance signal bandwidth maximum differential output rated output power maximum power output volume level steps SW number of volume steps SW external speaker path EAR EAR HF line coupling line type speaker impedance operating conditions minimum load impedance signal bandwidth maximum differential output rated output power maximum power output volume level steps SW number of volume steps SW DC bridged gt 16 5 1kHz 15 15
48. ed for some time let s say few hundreds of ms then the battery voltage will be measured and when it drops below its maximum value a fixed time length charging pulse is issued As the battery approaches its full charge the off time will become longer hence the duty cycle of the pulses will decrease The battery is considered fully charged when the pulse duty cycle is less than a threshold value typically 10 the pulse charge stops and eventually the maintenance starts The last phase is not properly a charging phase since the battery at this point is fully charged and the process may stop after the final charge The maintenance charge provides an additional charging process to compensate for the charge leak typical of a Li lon battery It is done by issuing pulses with a fixed time length again few hundreds of ms and a duty cycle around 590 or less This last phase is not implemented in the GE864 internal charging algorithm so that the battery once charged is left discharging down to a certain threshold so that it is cycled from full charge to slight discharge even if the battery charger is always inserted This guarantees that anyway the remaining charge in the battery is a good percentage and that the battery is not damaged by keeping it always fully charged Li lon rechargeable battery usually deteriorate when kept fully charged Last but not least in some applications it is highly desired that the charging process restarts when the battery is dis
49. er Supply Design Guidelines e The desired output for the power supply is 3 8V hence due to the big difference between the input source and the desired output a linear regulator is not suited and shall not be used A switching power supply will be preferable because of its better efficiency especially with the 2A peak current load represented by the GE864 When using a switching regulator a 500kHz or more switching frequency regulator is preferable because of its smaller inductor size and its faster transient response This allows the regulator to respond quickly to the current peaks absorption e For car PB battery the input voltage can rise up to 15 8V and this should be kept in mind when choosing components all components in the power supply must withstand this voltage Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks 100 F tantalum capacitor is usually suited e Make sure the low ESR capacitor on the power supply output usually a tantalum one is rated at least 10V e For Car applications a spike protection diode should be inserted close to the power input in order to clean the supply from spikes protection diode should be inserted close to the power input in order to save the GE864 from power polarity inversion This can be the same diode as for spike protection An example of switching regulator with 12V input is ti9ev input switching regulator
50. er and receiver and in the levels be sure to get a true RS232 level translator not a RS485 or other standards By convention the driver is the level translator from the 0 3V UART level to the RS232 level while the receiver is the translator from RS232 level to 0 3V In order to translate the whole set of control lines of the UART you will need 5 driver 3 receiver NOTE The digital input lines working at 2 8VCMOS have an absolute maximum input voltage of 3 75V therefore the level translator IC shall not be powered by the 3 8V supply of the module Instead it shall be powered from a 2 8V 3 0V dedicated power supply This is because in this way the level translator IC outputs on the module side i e GE864 inputs will work at 3 8V interface levels stressing the module inputs at its maximum input voltage This can be acceptable for evaluation purposes but not on production devices NOTE In order to be able to do in circuit reprogramming of the GE864 firmware the serial port on the Telit GE864 shall be available for translation into RS232 and either it s controlling device shall be placed into tristate disconnected or as a gateway for the serial data when module reprogramming occurs Only RXD TXD GND and the On off module turn on pad are required to the reprogramming of the module the other lines are unused All applicator shall include in their design such a way of reprogramming the GE864 Mam AG
51. erent categories e handset earphone low power typically a handset e hands free earphone low power typically a headset e car kit speakerphone high power typically a speaker The three groups have different power requirements usually the first two applications need only few mW of power which can be directly drained from the GE864 pads provided a suited speaker is used This direct connect design is the cheaper and simpler solution and will be suited for the most of the earphone design requirements There s no need to decouple the output ear lines if a suited earpiece is y Reproduction forbidden without Telit Communications S p A written authorization All Right reserved 37 of 60 GC864 Hardware User Guide 1W0300694 Rev 3 07 02 06 connected For the last group the speakerphone a power amplifier is required to raise the output power up to 5 10W required in a car cabin application All the designs shall comply with the following guidelines e Where possible use a bridged earphone circuitry to achieve the maximum power output from the device e Keep the earphone traces on the PCB and wires as short as possible e f your application requires a single ended earpiece and you want a direct connection then leave one of the two output lines open and use only the other referred to ground Remember that in this case the power output is 4 times lower than the bridged circuit and may not be enough to en
52. erno dell applicazione dell utente dovra rispettare le indicazioni progettuali descritte in questo manuale DE Die Integration des GE864 GSM GPRS Mobilfunk Moduls in muB gemaB der in diesem Dokument beschriebenen Konstruktionsregeln erfolgen SL Integracija GSM GPRS GE864 modula uporabniski aplikaciji bo morala upoStevati projektna navodila opisana v tem priro niku SP La utilizaci n del modulo GSM GPRS GE864 debe ser conforme a los usos para los cuales ha sido dise ado descritos en este manual del usuario FR L int gration du module cellulaire GE864 GSM GPRS dans l application de l utilisateur sera faite selon les r gles de conception d crites dans ce manuel HE mum MOT onan 90 TANDAAN 5023 neni NN nv wpann mumopwa amba GE864 The information presented in this document is believed to be accurate and reliable However no responsibility is assumed by Telit Communication for its use nor any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent rights of Telit Communication other than for circuitry embodied in Telit products This document is subject to change without notice GC864 Hardware User Guide 10300694 Rev 3 07 02 06 2 Hardware Commands 2 1 Turning ON the GE864 To turn on the GE864 the pad ON must be tied l
53. g 2 E GND MODIFY DATE PATH home users area DESCRIPTION FILE NAME cs1139a cir DAI TELECOM EVK 2 Dai Telecom Group Mod 067 rev 1 11 02 ANNOTATION FORM PROJECT Furlan M 080705 AUDIO A 3 PROJECT SHEETN OF SHEETS DRAWING CODE DRAWN Serdi M 080705 VERIFIED Nonis R 080705 0276 4 5 30276SE11139A
54. ge output from the microphone is Mic Voltage Output dB 45 4 7 20 69 7 ABy ms corresponding to Mic Voltage Output 10 92772 3 3410 Vms in order to have a signal of 1 mV ms 10 dB lower than the nominal input for the GE864 external path on the GE864 internal mic inputs then the buffer must have a gain of Voltage GE864 intmic Mic Voltage Output 1 10 3 3 3 10 Hence in these conditions the signal level on the input pads of the internal mic of the GE864 is 10 dB 3 times higher than the microphone output and therefore the buffer has to gain 10 dB To calculate the resistor values it must be kept in mind that balancing the line will double the signal and hence already add 6 dB therefore the buffer must gain only 1 5 times The corresponding values for the resistors on the buffer could be if we keep the input resistance R711 gain R708 1 5 10 15 R719 gain 1 R720 1 5 1 10 5 The commercial values of 15 8 5 6 are then chosen As a consequence the values of the capacitors C726 and C727 shall be 726 1 21 8000 R719 3 5 102 F 727 1 217 8000 R711 1 2 10 F The commercial values of 3 3nF and 1nF are then chosen page 35 of 60 7 Speaker 7 1 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 Speaker lines characteristics and requirements The Telit GE864 provides two audio paths for both th
55. he battery terminals still raises but at a lower rate Once the battery voltage reaches its maximum voltage then the process goes into its third state Final charging The voltage measure to change the process status into final charge is very important It must be ensured that the maximum battery voltage is never exceeded otherwise the battery may be damaged and even explode Moreover for the constant voltage final chargers the constant voltage phase final charge must not start before the battery voltage has reached its maximum value otherwise the battery capacity will be highly reduced The final charge can be of two different types constant voltage or pulsed GE864 uses constant voltage The constant voltage charge proceeds with a fixed voltage regulator very accurately set to the maximum battery voltage and hence the current will decrease while the battery is becoming charged Nga BARAN a Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 13 of 60 GC864 Hardware User Guide 1vv0300694 Rev 3 07 02 06 When the charging current falls below a certain fraction of the fast charge current value then the battery is considered fully charged the final charge stops and eventually starts the maintenance The pulsed charge process has no voltage regulation instead the charge continues with pulses Usually the pulse charge works in the following manner the charge is stopp
56. he distance between the microphone and the talker must be taken into account when designing the microphone amplifier For a car cabin usually the distance between the talker and the mic is about 50cm in these conditions the attenuation can be considered a thumb rule around 20dB Another thing to consider especially for cabin car use is the fact that the external mic will pick up also ambient noise to overcome this problem it is preferable to set the gain of the microphone 10dB lower with respect to the calculated value for a nominal sensitivity The corresponding reduction in signal level will be compensated by an increased voice volume of the talker which will speak louder because of the ambient noise For the headset we shall distinguish two different types the headsets having the microphone sustained close to the mouth and the headsets having the microphone on the earpiece cable The same considerations for the additional voice attenuation due to the distance from the microphone and the noise pick up can be made for the headset having the microphone on the earpiece cable while the other kind of headset shall be threaten as an handset For example With the external mic having the suggested nominal sensitivity 45dBymspa at the normal spoken conditions 4 7dB at 7 cm from the mouth of the talker and with a further attenuation of 20dB due to the distance from the microphone about 50 cm At that acoustic pressure the voltage
57. ically reducing the sleep comsumption to few pA In battery powered devices this feature will greatly improve the autonomy of the device 8 4 Using the Buzzer Output GPIO 07 BUZZER The GPIO 07 BUZZER pad when configured as Buzzer Output is controlled by the GE864 module and will drive with appropriate square waves a Buzzer driver This permits to your application to easily implement Buzzer feature with ringing tones or melody played at the call incoming tone playing on SMS incoming or simply playing a tone or melody when needed by your application A sample interface scheme is included below to give you an idea of how to interface a Buzzer to the GPIO 07 BUZZER Q102 s2F 2101 SOT 23 SMUS 1 227 SMBT2907A GPIO7 NOTE To correctly drive a buzzer a driver must be provided its characteristics depend on the Buzzer and for them refer to your buzzer vendor GC864 Hardware User Guide 10300694 Rev 3 07 02 06 9 Camera 91 Camera characteristics The GE864 module provides a direct support for digital cameras with the following characteristics Type TRANSCHIP TC5747 Technology CMOS COLOR camera Max picture size VGA 480x640 pixels landscape Output format JPEG Sensitivity 4 Lux 9 1 1 Camera interface connectors The 24 pads ZIF connector provides the interface connection between GE864 and camera GE864 ZIF 5243
58. imestamp 0 1 time only 2 data only 3 time amp data OK Taking an reading a photo gt 1 gt take photo OK gt AT OBJL see photo dimension OBJL Snapshot 38900 where 38900 is the file dimension in bytes of the photo taken OK gt AT RPHOTO download the photo data where data Correspond to the photo data in binary OK gt AT TPHOTO OK gt Repeating photo capture and download times data OK gt camera OFF ns em Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 47 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 10 Conformity Assessment Issues The GE864 module is assessed to be conform to the R amp TTE Directive as stand alone products so If the module is installed in conformance with Dai Telecom installation instructions require no further evaluation under Article 3 2 of the R amp TTE Directive and do not require further involvement of a R amp TTE Directive Notified Body for the final product In all other cases or if the manufacturer of the final product is in doubt then the equipment integrating the radio module must be assessed against Article 3 2 of the R amp TTE Directive In all cases assessment of the final product must be made against the Essential requirements of the R amp TTE Direct
59. ing call condition NOTE According to V 24 RX TX signal names are referred to the application side therefore on the GE864 side these signal are on the opposite direction TXD on the application side will be connected to the receive line here named TXD rx of the 864 serial port and viceversa for RX TIP For a minimum implementation only the TXD and lines can be connected the other D lines can be left open provided a software flow control is implemented The signals in the UART connector on the EVK2 are DCD RXD TXD DTR GND DSR RTS CTS RI GND GC864 Hardware User Guide 10300694 Rev 3 07 02 06 5 1 RS232 level translation In order to interface the GE864 with PC com port or a RS232 EIA TIA 232 application a level translator is required This level translator must invert the electrical signal in both directions change the level from 0 3V to 15 15V Actually the RS232 UART 16450 16550 16650 amp 16750 chipsets accept signals with lower levels on the RS232 side EIA TIA 562 allowing for a lower voltage multiplying ratio on the level translator Note that the negative signal voltage must be less than OV and hence some sort of level translation is always required The simplest way to translate the levels and invert the signal is by using a single chip level translator There are a multitude of them differing in the number of driv
60. istics are different from the suggested then it is preferable to use an amplifier to increase the power and current output capabilities Again the output from the GE864 is bridged and both lines should be used where possible as inputs to the power amplifier This ensures a higher common mode rejection ratio reducing the GSM current busts noise on the speaker output In this case the EAR MT lines from the GE864 should be AC coupled with a capacitor of 100nF It is always desirable to have a mute control on the amplifier in order to turn it off while the device is not sending signal to the output in this manner the amplifier background noise which may be audible during idle conditions is cut off A principle schematic may be page 38 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 EAR 1 EAR MT 100nF MOOnF The resulting gain and high pass cut can be obtained with the formula Gain 6 R2 1 req Hz freq NA And an example of internal Ear amplifier is INTERNAL EAR AMPLIFIEA UB01 uy ba o Ox Mer ow 55 u5 5 TO SPEAKER 4 jun n L4 5 1 CH SHUTDONN a z ap HS FROM GM862 EAR CT BYPASS ca21 7 nala 1 Jan M AS
61. ive Articles 3 1 a and b safety and EMC respectively and any relevant Article 3 3 requirements The GE864 module is conform with the following European Union Directives R amp TTE Directive 1999 5 EC Radio Equipment amp Telecommunications Terminal Equipments e Low Voltage Directive 73 23 EEC and product safety e Directive 89 336 EEC for conformity for EMC In order to satisfy the essential requisite of the R amp TTE 99 5 EC directive the GE864 module is compliant with the following standards e GSM Radio Spectrum Standard EN 301 511 and 3GPP 51 010 1 e EMC Electromagnetic Compatibility Standards EN 301 489 1 and EN 301 489 7 LVD Low Voltage Directive Standards EN 60 950 In this document and the Hardware User Guide Software User Guide all the information you may need for developing a product meeting the R amp TTE Directive is included The GE864 module is conform with the following US Directives e Use of RF Spectrum Standards FCC 47 Part 24 GSM 1900 e EMC Electromagnetic Compatibility Standards FCC47 Part 15 To meet the FCC s RF exposure rules and regulations The system antenna s used for this transmitter must be installed to provide a separation distance of at least 20 cm from all the persons and must not be co located or operating in conjunction with any other antenna or transmitter The system antenna s used for this module must not exceed 3 dBi for mobile and fixed or mobile operating configurations U
62. ll Right reserved page 30 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 6 3 2 Unbalanced Microphone biasing The unbalanced microphone biasing voltage should be obtained from a dedicated voltage regulator in order to eliminate the noise present on the power lines This regulator can be the same for all the audio paths The microphone should be supplied from a capacitor multiply circuit For example a circuit for the unbalanced microphone biasing can be 3V MIC 4 4 U1 LP2SB0AIMBX 3 0 4 amp an 1 T GND 3 A ON OFF NC X H Av 5 i 0402 5 c A Electret microphone rd Een ea re PA Snielded i Cable Mga i seco oe ob MICH To Mic Buffer amplifier MIC NOTE In the unbalanced application the capacitor C3 shall be gt 200nF otherwise the frequency response will be cut at low band frequencies down to 300Hz This capacitor can be placed close to the MIC pad EXT_MIC or INT_MIC depending on the audio path chosen or if possible it should be placed close to the shielded cable connector If the ground return path is well desig
63. ly automotive Battery 3 2 1 1 5V input Source Power Supply Design Guidelines Reproduction forbidden without Telit Communications S p A written authorization All Right reserved 10 of 60 The desired output for the power supply is 3 8V hence there s not a big difference between input source and the desired output and a linear regulator can be used A switching power supply will not be suited because of the low drop out requirements When using a linear regulator a proper heat sink shall be provided in order to dissipate the power generated A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks close to the GE864 a 1001 tantalum capacitor is usually suited Make sure the low ESR capacitor on the power supply output usually a tantalum one is rated at least 10V A protection diode should be inserted close to the power input in order to save the GE864 from power polarity inversion Mam AG GC864 Hardware User Guide 10300694 Rev 3 07 02 06 An example of linear regulator with 5V input is 45v input linear regulator 3 17152866 INPUT Reproduction forbidden without Communications written authorization All Right reserved page 11 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 3 2 1 2 12V input Source Pow
64. ly connected to the Ground Plane by placing vias once per 2mm at least e Place EM noisy devices as far as possible from GE864 antenna line e Keep the antenna line far away from the GE864 power supply lines If you have EM noisy devices around the PCB hosting the GE864 such as fast switching ICs take care of the shielding of the antenna line by burying it inside the layers of PCB and surround it with Ground planes or shield it with a metal frame cover e f you don t have EM noisy devices around the PCB of GE864 by using a strip line on the superficial copper layer for the antenna line the line attenuation will be lower than a buried one page 18 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 4 3 Antenna installation Guidelines e Install the antenna in a place covered by the GSM signal The Antenna must be installed to provide a separation distance of at least 20 cm from all persons and must not be co located or operating in conjunction with any other antenna or transmitter e Antenna shall not be installed inside metal cases e Antenna shall be installed also according Antenna manufacturer instructions Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 19 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 5 Serial Port The serial port on the Telit GE864 is the core of the interface between the module
65. m 100 3 0V USB SES 38 LP2981AIM5X 3 0 NOPB GND 526 O H3 BDBUS3 37 5 TT 1 our VIN 527 O GND 25 NAN l Ha C509 C510 GND TP528 BDBUSS 39 GND i 100nF 8 DU os 5 8 XSR 10uF 4 Ic ON OFF 6 33 2 3 8 99 10V 10 63V 35V USB Eng 1132 a ER gt gt ul 24 SCL HW 0402 0603 BDBUS7 E ESO ADBUSO CJ MAOSA 6 1 2 SDA HW db R524 U507 4B GND 18K 93LCS6B I SNG Buso 30 ADBUS2 22 db m 5V_USB ei bo p 5 BCBUSI Ba 21 1 506 1 les vecl 8 5 BCBUS2 ADBUS4 20 a 2 nca x 9 Us MS 3 BUS3 Sa 3 USBDP ADBUSS 45V USB 3 lot VPEA BCBUS3 m 3 LT YE si 26 TG 2 ADBUSG 7 R536 e 5 NO 5 16 E RSTOUT ADBUS7 vus 42 5S R338 3 257 za 2 4 RESET 77 48 5 ey fe REN 516 RA noMount YES Acon 18 SND 2 lt o o XTIN_FT2232 o gt ACBUS1 H n SA 9C E3 negas AcBus2 H gt gt 9 JP504 acsuss H GND 4 m5 LDO_ON_OFF 24 suwua 10 3 6C 3 7B 4 6E 2B 8C E a B 1 11B 3 6C 3 7B 4 6E 2B 8C 48 EECS 1503 lt i ES FT2232L 4 RX PROG USB 7M 2 LQFP48 1 39
66. mode noise rejection reducing the 216 Hz burst noise produced during the GSM transmissions e Where possible use balanced microphone circuitry e Keep the microphone traces on the PCB and wires as short as possible e f your application requires an unbalanced microphone then keep the lines on the PCB balanced and unbalance the path close to the microphone wire connector if possible e For the microphone biasing voltage use a dedicated voltage regulator and a capacitor multiply circuit e Make sure that the microphone traces in the PCB don t cross or run parallel to noisy traces especially the power line e f possible put all around to the microphone lines a ground trace connected to the ground plane several vias This is done in order to simulate a shielded trace on the PCB e The biasing circuit and eventually the buffer can be designed in the same manner for the internal and external microphones 6 3 Microphone Biasing The electret microphones usually need a biasing voltage to work properly Refer to your microphone provider for the characteristics required NOTE The microphones have a hot wire were the positive biasing must be connected usually it is indicated by a sign or a red point If the polarity of the bias is reversed then the microphone will not work properly For this reason be sure to respect the mic biasing polarity GC864 Hardware User Guide 10300694 Rev 3 07 02 06 6 3 1 Bal
67. ned then it is possible to eliminate the C3 capacitor provided the buffer is close to the mic input NOTE The cable to the microphone should be shielded NOTE The microphone sensitivity changes with the value of R2 Usually the microphones are characterized with 2kQ biasing resistance so try to keep the value of R2 around 2kQ For mic characteristics refer to the manufacturer page 31 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 6 4 Microphone buffering As seen previously a microphone shall be connected to the input pads of the GE864 through a buffer amplifier that boosts the signal level to the required value Again the buffered microphone circuitry can be balanced or unbalanced Where possible it is always preferable a balanced mic solution The buffering circuit shall be placed close to the microphone or close to the microphone wire connector 6 4 1 Buffered Balanced Mic A sample circuit can be A BALANCED MICROPHONE BUFFER 24 dB 43 i T 34 R516 os 5 m DECOUPLING CAPACITORS END UOZ m en ELCHE CE QE 4 153 9121 ok ul gt Oz v wos 25 2 4 4 Lo og 5 C687 R615 do n8 100nF m TO FROM i MEE ia S8 GM862 MIC m 1
68. other signals allowed Cold End Ground Plane of antenna shall be equipotential to the GE864 ground pins Furthermore if the device is developed for the US market and or Canada market it shall comply to the FCC and or IC approval requirements This device is to be used only for mobile and fixed application The antenna s used for this transmitter must be installed to provide a separation distance of at least 20 cm from all persons and must not be co located or operating in conjunction with any other antenna or transmitter End Users must be provided with transmitter operation conditions for satisfying RF exposure compliance OEM integrators must ensure that the end user has no manual instructions to remove or install the GE864 module Antennas used for this OEM module must not exceed 3dBi gain for mobile and fixed operating configurations 4 2 Antenna PCB line Guidelines e Ensure that the antenna line impedance is 50 ohm e Keep the antenna line on the PCB as short as possible since the antenna line loss shall be less than 0 3 dB e Antenna line must have uniform characteristics constant cross section avoid meanders and abrupt curves e Keep if possible one layer of the PCB used only for the Ground plane e Surround on the sides over and under the antenna line on PCB with Ground avoid having other signal tracks facing directly the antenna line track e The ground around the antenna line on PCB has to be strict
69. output from the microphone is Voltage Output dB 45 4 7 20 69 7 corresponding to Voltage Output 10 997 20 3 3 10 4 Vms GC864 Hardware User Guide 1W0300694 Rev 3 07 02 06 by having the microphone gain set to 10 dB corresponding to 3 times the signal in the nominal conditions on the input external mic pads of the GE864 will be Voltage GE864 extmic 3 3 10 3 1 MVms Hence these conditions the signal level the input pads of the external mic of the GE864 is 10 3 times lower than the nominal as suggested The microphones usually need a biasing network that provides the necessary DC current to the mic this will be explained further on In the 2 all the microphone input jacks have the hot wire connected to the central pole NEM AA p E Reproduction forbidden without Telit Communications S p A written authorization Right reserved page 28 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 6 2 General Design Rules There are several configurations for the audio path but the most effective difference is between balanced and unbalanced microphone It is highly recommended to keep the whole microphone path balanced even if this means having 2 wires connecting the microphone instead of one needed plus ground in the unbalanced case The balanced circuitry is more suited because of its good common
70. ow for at least 1 second and then released The maximum current that can be drained from the ON pad is 0 1 mA A simple circuit to do it is ON Power ON impulse GO 777 END NOTE don t use any pull up resistor on the ON line it is internally pulled up Using pull up resistor may bring to latch up problems on the GE864 power regulator and improper power on off of the module The line ON must be connected only in open collector configuration NOTE In this document all the lines that are inverted hence have active low signals are labeled with a name that ends with a or with a bar over the name NOTE The GE864 turns fully on also by supplying power to the Charge pad provided there s a battery on the VBATT pads d Pa Reproduction forbidden without Telit Communications S p A written authorization All Right reserved page 5 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 For example 1 Let s assume you need to drive the ON pad with a totem pole output of a 3 5 V microcontroller gt ON 3 5 53 02 uP DUT1 4 eu 2 SOT 323 i 1 5 cris OMEN AFE C 5 T 0402 Power ON OFF inpulse e GND 2 Let s assume you need to drive the pad directly with an ON OFF button OND page 6 of 60 GC864 Hardware User
71. ower Saving disabled 19 The GSM system is made in a way that the transmission is not continuous else it is packed into bursts at a base frequency of about 216 Hz the relative current peaks can be as high as about 2A Therefore the power supply has to be designed in order to withstand with these current peaks without big voltage drops this means that both the electrical design and the board layout must be designed for this current flow If the layout of the PCB is not well designed a strong noise floor is generated on the ground and the supply this will reflect on all the audio paths producing an audible annoying noise at 216 Hz if the voltage drop during the peak current absorption is too much then the device may even shutdown as a consequence of the supply voltage drop TIP The electrical design for the Power supply should be made ensuring it will be capable of a peak current output of at least 2 A GC864 Hardware User Guide 10300694 Rev 3 07 02 06 3 2 General Design Rules The principal guidelines for the Power Supply Design embrace three different design steps the electrical design the thermal design the PCB layout 3 2 1 Electrical design Guidelines The electrical design of the power supply depends strongly from the power source where this power is drained We will distinguish them into three categories 5V input typically PC internal regulator output 12V input typical
72. re AT command If the echo canceller is left active with the headset then some echo might be introduced by the echo cancel algorithm The nominal sensitivity of the line indicates the voltage level on the GE864 pads that should be present during normal spoken conditions for a handset a voice signal coming from the mouth of the Telit GC864 Hardware User Guide 1vv0300694 Rev 3 07 02 06 talker at 7 cm of distance from the microphone producing an acoustic pressure of 4 7 1 kHz on the microphone membrane For example With the internal mic having the suggested nominal sensitivity 45dByimspa at the normal spoken conditions 4 7dB on the microphone membrane At that acoustic pressure the voltage output from the microphone is Voltage Output dB 45 4 7 49 7 ABy ms corresponding to Voltage Output 10 97 20 3 3 10 3 Vms by having the microphone gain set to 24 dB corresponding to 15 8 times the signal in the nominal conditions on the input mic pads of the GE864 will be Voltage GE864 mic 3 3 4103 15 8 51 mV During the spoken conditions the signal varies according to the volume of the voice of the talker usually a rough thumb rule for the dynamic range may be considered 20dB 10 times at maximum voice level talker screaming 50 dB 1 300 times at minimum voice level talker whispering For the handsfree car kit microphone the voice attenuation due to t
73. sers and installers must be provided with antenna installation instructions and transmitter operating conditions for satisfying RF exposure compliance Manufacturers of mobile fixed or portable devices incorporating this module are advised to clarify any regulatory questions and to have their complete product tested and approved for FCC compliance page 48 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 11 SAFETY RECOMMANDATIONS READ CAREFULLY Be sure the use of this product is allowed in the country and in the environment required The use of this product may be dangerous and has to be avoided in the following areas Where it can interfere with other electronic devices in environments such as hospitals airports aircrafts etc Where there is risk of explosion such as gasoline stations oil refineries etc It is responsibility of the user to enforce the country regulation and the specific environment regulation Do not disassemble the product any mark of tampering will compromise the warranty validity We recommend following the instructions of the hardware user guides for a correct wiring of the product The product has to be supplied with a stabilized voltage source and the wiring has to be conforming to the security and fire prevention regulations The product has to be handled with care avoiding any contact with the pins because electrostatic discharges may damage the product itself S
74. sitivity 45dByrmspaat the normal spoken conditions 4 7 at 7 cm from the mouth of the talker At that acoustic pressure the voltage output from the microphone is Mic Voltage Output dB 45 4 7 49 7 corresponding to Mic Voltage Output 10 7 20 3 3 10 Vins in order to have a signal of 50 on the GE864 internal mic inputs then the buffer must have a gain of Voltage GE864_intmic Mic Voltage Output 50 10 3 3 10 15 Hence in these conditions the signal level on the input pads of the internal mic of the GE864 is 24 dB 15 times higher than the microphone output and therefore the buffer has to gain 24 dB The corresponding values for the resistors on the buffer could be if we keep the input resistance R604 R606 gain R603 gain R605 15 10 150 The commercial values of 150 amp are then chosen As a consequence the values of the capacitors C636 and C637 shall be C636 C637 1 211 8000 R606 132 10 7 A commercial value of 100pF is then chosen page 33 of 60 GC864 Hardware User Guide 10300694 Rev 3 07 02 06 6 4 2 Buffered Unbalanced Single Ended Mic A sample schematic for a buffered unbalanced single ended microphone can be SINGLE ENDED MICROPHONE BUFFER 10 d3v EXT MIG SINMBELE
75. sure a good voice volume e Make sure that the earphone traces in the PCB don t cross or run parallel to noisy traces especially the power line e The cable to the speaker shall be a twisted pair with both the lines floating for the bridged output type shielded with the shield to ground for the single ended output type 7 21 Noise Filtering The of the PCB should have a noise filter close to the connector to filter the high frequency GSM noise The filter can be a of 2 capacitor and a inductance with the one capacitor of 39pF 0603 case and the other capacitor of 1nF 0603 the inductance shall have a value of 39uH 7 3 Handset earphone design As seen previously 160 speaker be directly connected to the output pads EAR and EAR the GE864 This solution is often the more cost effective reducing the components count to a minimum There are several limitations to the use of this solution speaker direct connect imposes the speaker characteristics to be almost exactly the suggested ones otherwise the power output may be reduced if speaker impedance is bigger than 160 or the GE864 ear port may be damaged if speaker impedance is less than 150 The other limitation of the speaker direct connection is the power output capability of the GE864 which is limited and for some particular applications may not be enough For these reasons when the power output of the GE864 is not enough or if the speaker character

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