AT90USBKey Hardware User Guide
Contents
1. NOW eui 0 pasala Joyoede qvon 90H 0 vH 0904 0904 09010080d 09010080d L v 91z60 m4 Ko gert INIA r nh Hg 19 JaviuW gen OT odd 6 ssd din SE 9n9 ave oH L dvon ez EH 9 ONDNUNS Non q 0906 VV ba DOAN b zz ou SONA T 13d NOOAn 99 XTBNSSSV tr L 93d gt gt NOAN NOW au 01 p solO SHOISIS3H d q 0909 400 NOW ay 0 Desom Joyoedeo 9 eiue 6 19 AT90USBKey Hardware User Guide 7627A AVR 04 06 Figure 6 2 Schematics 2 of 2 Complete Schematics Sx NOD NOD OVIP WW PET you AH JequinN juawnsoq azig ddd seoe eju 9 1 MOd enu Aen gengen UIV Sid vid 4001 624 A AE RE E HOT 0 H 0 Z sd HOLO3NNOO JHL OL 350719 0 HOLIDVdVO S9NIdnoo3d ozy yozz uone oads 510 4 9 gt snaA deo 4 H Ka S0EJ19YU1 OWLS 2 apow LSOH OLO 10 Joje eub sng AT90USBKey Hardware User Guide lt sngA SOON vn d iii Pequnow jou 3Tnegep TEM NOLL Zo7jeTNbai Teuz qur Tn WOZZ GE Sift UOW 398A Zosuas duer 3001 hZ Se Atddns zemod 3xg 1497 duy Se Sang m Ex Bess N A Seu EMS ONT Ee E 819 119 2 IN ay gu0ot dE SEN T sSng amp lt TET zZ sr IY dP08NG4 Em sii pejunow 30u TEM iii i i NG Sl Wal T i 614 6 LY SLY S1H 1 97 FIN0EN T STO2. Ne eR i E C7 Us ES E ES 5 INR ean care d Fle EWE RIO RY Ven ae 10 nr x PL m DIE LJ oo Fanas 2 e o o O na 3s AT90USBKey Hardware User Guide 1 3 7627A AVR 04 06 Introduction 1 2 AT90USBKey Features 1 4 7627A AVR 04 06 The AT90USBKey provides the following features AT90USB QFN64 AVR Studio software interface USB software interface for Device Firmware Upgrade DFU bootloader Power supply flagged by VCC ON LED regulated 3 3V from an external battery connector for reduced host or OTG operation from the USB interface USB device bus powered application JTAG interface connector not mounted for on chip ISP for on chip debugging using JTAG ICE Serial interfaces 1 USB full low speed device host OTG interface On board resources 4 1 ways joystick 2 Bi Color LEDs temperature sensor serial dataflash memories all microcontroller I O ports access on 2x8pin headers not mounted m On board RESET button W On board HWB button to force bootloader section execution at reset m System clock Notes 1 The AVRUSBKey is supported by AVR Studio version 4 12 or higher For up to date information on this and other AVR tool products please consult our web site The most recent version of AVR Studio8 AVR tools and this User Guide can be 8 MHz crystal found in the AVR section of the Atmel web site http www atmel com 2 ATME
3. Debugging with AVR JTAG ICE mkll The AT90USBKey can be used for debugging with JTAG ICE MK II Connect the JTAG ICE mkll as shown in Figure 2 10 for debugging please refer to AVR Studio Help information When using JTAG ICE MK II for debugging and as AT90USB parts are factory configured with the higher security level set a chip erase operation will be performed on the part before debugging Thus the on chip flash bootloader will be erased It can be restored after the debug session using the bootloader hex file available from ATMEL website 7627A AVR 04 06 AIMEL T Section 3 Troubleshooting Guide Figure 3 1 Troubleshooting Guide Problem The Green VCC ON LED is not on AVRUSBKey does not work Reason No power supply Solution Verify the power supply source check battery charge or USB connection The AT90USB cannot be programmed The AVR JTAG ICE probe is not connected Connect the JTAG ICE 10 PIN header to the correct AVRUSBKey JTAG header page 13 The memory lock bits are programmed Erase the memory before programming with JTAG ICE The fuse bits are wrongly programmed Check the fuse bits with JTAG ICE Can not connect to USB bootloader Force bootloader execution with HWB under reset USB bootloader erased after a JTAG debugging session reprogram the USB bootloader with JTAG AVR Studio does not detect the AVR JTAG ICE Serial U
4. i 81H l 3001 ZEN 8P1711 H ra i 13S GNO i KK b i a ad Linvs grip i ms 1nO Mous i t 1no NI i ACC jezsuab 03 sMOTTY pequnow jou pn pejunow jou oZ teg butqjunow ueuM T 8NOSVO dar9gast LY dM so pr Bi OOA 13S4U 13534 L ano wett St 3001 Tl os is LZ cad eiu 8 L AL ely EI 929N 41 aao 4 031 u3 0d 391440 3HL OL 3S019 HOLIOVdVO 9NA NOA SOON 391430 3HL OL 3SO 19 HOLIOVdVO DNITdNOO3A 99 6 20 7627A AVR 04 06 Table 6 1 Bill of material Complete Schematics Item Q ty Reference Part MSS Package 1 2 CR1 CR2 ESD protection PGB0010603 2 10 C1 C2 C3 C4 C5 C6 C12 100nF 50V 10 Ceramic CASE 0603 C13 C18 C20 3 1 C7 1uF 10Vmin 10 EIA IECQ 3216 4 3 C8 C9 C17 220nF 50V 10 Ceramic CASE 0603 5 2 C10 C11 15pF 50V 5 Ceramic CASE 0608 6 3 C14 C16 C19 4 7uF 10Vmin 10 EIA IECQ 3216 7 1 C15 33nF 50V 5 Ceramic CASE 0603 8 2 D2 D5 LED BI COLOUR LSGT670 l 10 mA_ PLCC 4 9 1 D1 TOPLED LPM676 K2M1 I 10 mA PLCC 2 10 2 D3 D4 DII LL4148 7 is200mA max LL 34 11 1 JJ USB mini AB receptacle Surface mount 12 0 J9 CON 2x5 2 54mm Not Mounted 13 0 J1 J2 4 5 J6 J7 1 27 mm Dual header Not Mounted 14 1 J8 Connector MTA 2 cts right angle 15 1 M1 FDV304P FAI SOT23 16 1 Q1 BC847B I
5. the AVR tools found on the PCB Version number of AVR Studio This can be found in the AVR Studio help menu PC operating system and version build PC processor type and speed A detailed description of the problem AT90USBKey Hardware User Guide 5 17 7627A AVR 04 06 AMEL Section 6 Complete Schematics On the next pages the following documents of AT90USBKey are shown B Complete schematics W Bill of materials AT90USBKey Hardware User Guide 6 18 7627A AVR 04 06 Complete Schematics 001 nay 9002 60 Menuer Aepuoyy lt o0q gt 1 quunN jueunooq vy azig Add enu Kay asnoev ewsid za uns 090H 62 NV 0900 ZH UOTJEATJOY Tepeot joog h El 8MH PIETA teng ww z iL eo eo Figure 6 1 Schematics 1 of 2 Eidel AUOOL 0909 3u00L guid NOW 391430 AHL OL Q3SO1O HOLIOVdVO ONINdNOOAG Teuid NOW 391430 3HL OL Q3SO 19 SHOLIOVdVO ONMNdNODAG eSuld NOW 39IA3G AHL OL GASO019 HOLIOVdVO DNITdNO 93 isu 3Tn2412 3 s w ENSLO h 1SH lozlod OE oon 19d 10d 293 gad E7 vd EA Gie E dag SNEF dag HO ZHW8 019 J 1 ISAY AL LA LINZ lt eWIX vONAO YONAO 82LASNOGLV OND gt EEEESEEEEEEEEE KEEN n n N n N N N NM NOOO OOP ON OTT ONDV HOIAAG JHL OL Q3S010 SHOLSISIYH
6. 19 196 94 6 847 AMEL 7627A AVR 04 06 Using the AT90USBKey Temp RT Temp RT Temp RT Temp RT C KQ C KQ C KO C KO 5 278 995 35 62 937 65 18 493 95 6 635 6 264 119 36 60 188 66 17 820 96 6 430 7 250 134 37 57 576 67 17 174 97 6 233 8 236 981 38 55 093 68 16 556 98 6 043 9 224 606 39 52 732 69 15 964 99 5 860 Figure 2 8 Thermistor Schematic 2 4 5 Data Flash memory For mass storage class demonstration purpose the AT90USBKey provides two on chip serial Flash memories AT45DB642D connected to the AT90USB Serial Port Interface SPI The data flash chip select signals are connected to PortE bit 0 and bit 1 of the AT90USB See Figure 2 9 Figure 2 9 On board data flash schematic 2 12 7627A AVR 04 06 AMEL PF 7 0 AT90USBKey Hardware User Guide Using the AT90USBKey 2 5 In System Programming 2 5 1 Programming with USB bootloader DFU Device Firmware Upgrade AT90USB part comes with a default factory pre programmed USB bootloader located in the on chip boot section of the AT90USB This is the easiest and fastest way to reprogram the device directly over the USB interface The Flip PC side application is available from the Atmel website offers a flexible an user friendly interface to reprogram the application over the USB bus The HWB pin of the AT90USB allows to force the bootloader section ex
7. 44306 Nantes Cedex 3 France Tel 33 2 40 18 18 18 Fax 33 2 40 18 19 60 RF Automotive Theresienstrasse 2 Postfach 3535 74025 Heilbronn Germany Tel 49 71 31 67 0 Fax 49 71 31 67 2340 1150 East Cheyenne Min Blvd Colorado Springs CO 80906 USA Tel 1 719 576 3300 Fax 1 719 540 1759 Biometrics Imaging Hi Rel MPU High Speed Converters RF Datacom Avenue de Rochepleine BP 123 38521 Saint Egreve Cedex France Tel 33 4 76 58 30 00 ASIC ASSP Smart Cards Zone Industrielle 13106 Rousset Cedex France Tel 33 4 42 53 60 00 Fax 33 4 42 53 60 01 Chinachem Golden Plaza Fax 33 4 76 58 34 80 77 Mody Road Tsimshatsui East Kowloon Hong Kong Tel 852 2721 9778 Fax 852 2722 1369 1150 East Cheyenne Mtn Blvd Colorado Springs CO 80906 USA Tel 1 719 576 3300 Fax 1 719 540 1759 Japan 9F Tonetsu Shinkawa Bldg 1 24 8 Shinkawa Chuo ku Tokyo 104 0033 f Japan Scottish Enterprise Technology Park Tel 81 3 3523 3551 Maxwell Building Fax 81 3 3523 7581 East Kilbride G75 0QR Scotland Tel 44 1355 803 000 Fax 44 1355 242 743 Literature Requests www atmel com literature Disclaimer The information in this document is provided in connection with Atmel products No license express or implied by estoppel or otherwise to anyintellectu alproperty right is granted by this document or in connection with the sale of Atmel products EXCEPT AS SET FORTH IN ATMEL S TERMS AND CONDI TI
8. AT90USBKey Hardware User Guide AMEL Section 1 amp eike elle ie EE 1 3 EESTI 1 3 1 2 AT90USBKey Features ana UU ua ee ee ee ee ee Re ee ee ee 1 4 Section 2 Using die AT90USBK6y 2 5 GN DS 2 5 2 2 Power SUPPLY u uuu ts ee aah dane ean 2 6 2 3 ME N OE AA 2 8 2 4 On board Hesources I U UU AR I ee ee ee ee ee ee ee ede 2 9 2 5 In System Programming se a EE Ge ee eene 2 13 2 6 Debuggingi ei ee ge Eg dee tee Edge 2 14 Section 3 Troubleshooting Guide aaa NAT AA 3 15 Section 4 Technical Specifications Ae 4 16 Section 5 Technical bell sels RR Rt 5 17 Section 6 Complete ENEE 6 18 AT90USBKey Hardware User Guide User Guide 1 7627A AVR 04 06 AIMEL Section 1 Introduction Congratulations on acquiring the AVR amp AT90USBKey This kit is designed to give designers a quick start to develop code on the AVR and for prototyping and testing of new designs with the AT90USB microcontroller family 1 1 Overview This document describes the AT90USBKey dedicated to the AT90USB AVR microcontroller This board is designed to allow an easy evaluation of the product using demonstration software To increase its demonstrative capabilities this stand alone board has numerous on board resources USB joystick data flash and temperature sensor Figure 1 1 AT90USBKey cor TYGER is R24 ET ele Ve rap ri PS PH of DL D T A d se m E ES
9. C peak 200mA SOT23 17 2 R2 R3 22 1 16W 5 SMD CASE 0603 18 1 R5 68k 1 16W 5 SMD CASE 0603 19 2 R6 R7 47k 1 16W 5 SMD CASE 0603 20 7 R1 R4 R5 R8 R16 R20 R26 0 CASE 0603 21 0 R21 0 Not Mounted CASE 0603 22 1 R28 220k 1 16W 5 SMD CASE 0603 23 7 R9 R10 R11 R12 R25 R27 R3 100k 1 16W 5 SMD CASE 0603 0 24 5 R13 R14 R17 R22 R23 1k 1 16W 5 SMD CASE 0603 25 2 R24 R28 10k 1 16W 5 SMD CASE 0603 26 1 R29 NCP18WF104J03RB 100K B 4250 CASE 0603 27 2 R15 R18 100k 1 1 16W 1 SMD CASE 0603 28 1 R19 120k 196 1 16W 1 SMD CASE 0603 29 2 SW1 SW2 PUSH BUTTON DTSM31N 6x3 5mm 1 6N See DS 30 1 SW3 TPA511G 4 ways joystick center CMS mount 31 1 U1 AT90USB1287 QFN64 32 2 U2 U3 AT45DB642D CASON8 33 1 U4 LP3982IMM ADJ Vin Max 6V 300mA MSOP8 34 1 US LM340MP5 0 35 1 Yi 8MHz CRYSTAL H 4mm HC49 4H AT90USBKey Hardware User Guide AIMEL 6 21 7627A AVR 04 06 AIMEL www Atmel Corporation 2325 Orchard Parkway San Jose CA 95131 USA Tel 1 408 441 0311 Fax 1 408 487 2600 Regional Headquarters Europe Atmel Sarl Route des Arsenaux 41 Case Postale 80 CH 1705 Fribourg Switzerland Tel 41 26 426 5555 Fax 41 26 426 5500 Asia Room 1219 Atmel Operations Memory 2325 Orchard Parkway San Jose CA 95131 USA Tel 1 408 441 0311 Fax 1 408 436 4314 Microcontrollers 2325 Orchard Parkway San Jose CA 95131 USA Tel 1 408 441 0311 Fax 1 408 436 4314 La Chantrerie BP 70602
10. EL AT90USBKey Hardware User Guide Using the AT90USBKey 2 4 On board Resources 2 4 1 USB The AVRUSBKey is supplied with a standard USB mini A B receptacle The mini AB receptacle allows to connect both a mini A plug or a mini B plug connectors Figure 2 5 USB mini A B Receptacle When connected to a mini B plug the AT90USB operates as an USB device the ID pin of the plug is unconnected and when connected to a mini A plug the AT9OUSB operates as a USB host the ID pin of the A plug is tied to ground 2 4 2 Joystick The 4 1 ways joystick offers an easy user interface implementation for a USB application it can emulate mouse movements keyboard inputs Pushing the push button causes the corresponding signal to be pulled low while releasing not pressed causes an H Z state on the signal The user must enable internal pull ups on the microcontroller input pins removing the need for an external pull up resistors on the push button Figure 2 6 Joystick Schematic F Nl Select Left Up 4 Right Down TPA511G AT90USBKey Hardware User Guide AIMEL 2 9 7627A AVR 04 06 Using the AT90USBKey 2 4 3 2 4 4 2 10 LEDs Temperature Sensor 7627A AVR 04 06 The AT90USBKey includes 2 bi color LEDs green red implemented on one line They are connected to the high nibble of Port D of AT90USB PORTDI4 7 To light on a LED the corresponding port pin must drive a high level To light off
11. L Flip amp In System Programming Version 3 or Higher shall be used for Device Firmware Upgrade Please consult Atmel web site to retrieve the latex version of Flip and the DFU bootloader Hex file if needed AMEL AT90USBKey Hardware User Guide AMEL Section 2 Using the AT90USBKey This chapter describes the AVRUSBKey and all its resources 2 1 Overview Figure 2 1 AT90USBKey Overview AT90USBKey Hardware User Guide 2 5 7627A AVR 04 06 Using the AT90USBKey 2 2 Power Supply 2 2 1 Power Supply Sources The on board power supply circuitry allows two power supply configurations Mm from USB connector m from battery connector USB powered When used as a USB device bus powered application the AVRUSBKey can be directly powered via the USB VBUS power supply line Battery powered The external battery connector should be used when the AT90USBKey is used as a USB host This mode allows the AT90USBKey to provide a 5V power supply from its VBUS pin Need of a female battery clip Input supply from 8 up to 15V DC min 100mA Figure 2 2 Power supply schematic gt gt vCC3 LL4148 D4 LL4148 100k 1 R18 R19 124k 1 LL4148 d 4 7uF S 3 MTA Ext power supply 2 6 AIMEL AT90USBKey Hardware User Guide 7627A AVR 04 06 Using the AT90USBKey 2 2 2 VBUS Generator When using the AT90USB microcontroller in USB host mode the AT90USBKey should provide a 5V power supply o
12. ONS OF SALE LOCATED ON ATMEL S WEB SITE ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS IMPLIED OR STATUTORYWAR RANTY RELATING TO ITS PRODUCTS INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICU LARPURPOSE OR NON INFRINGEMENT IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT INDIRECT CONSEQUENTIAL PUNITIVE SPECIAL OR INCIDEN TAL DAMAGES INCLUDING WITHOUT LIMITATION DAMAGES FOR LOSS OF PROFITS BUSINESS INTERRUPTION OR LOSS OF INFORMA TION ARISING OUTOF THE USE OR INABILITY TO USE THIS DOCUMENT EVEN IF ATMEL HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAM AGES Atmel makes norepresentationsor warranties with respect to the accuracy or completeness of the contents of this document and reserves the right to make changes to specificationsand product descriptions at any time without notice Atmel does not make any commitment to update the information contained herein Unless specifically provided otherwise Atmel products are not suitable for and shall not be used in automotive applications Atmel s products are not intended authorized or warranted for useas components in applications intended to support or sustainlife Atmel Corporation 2006 All rights reserved Atmel logo and combinations thereof are registered trademarks and Everywhere You Are are the trademarks of Atmel Corporation or its subsidiaries Other terms and product names may be trademarks of others Ce Prin
13. SB cable is not connected or power is off Connect serial cable to RS232 STK500 AVR ISP and check power connections Connect serial cable to USB JATG ICE MKII AVR ISPmkIII and check power connections PC COM port is in use Disable other programs that are using PC COM port Change PC COM port AVR Studio does not detect COM port Disable COM port auto detection in AVR Studio file menu Force COM port to correct COM port AT90USBKey Hardware User Guide 3 15 7627A AVR 04 06 AMET Section 4 Technical Specifications B System Unit B Operating Conditions Internal Voltage Supply EE 3 3V External Voltage Supply uuu ua de ee ee ee ee ee ee ee ee 8V 15V B Connections USB Connector ee EE Se ee N denne Mini AB receptacle USB Communications esee Full speed low speed JTAG ConNEeCtOF ee ee ee ee Footprint for HE10 connector All ports Connechors ek J1 J2 J4 J5 J6 J7 Battery e ue MTA right angle AT90USBKey Hardware User Guide 4 16 7627A AVR 04 06 AMET Section 5 Technical Support For Technical support please contact avr atmel com When requesting technical support please include the following information Which target AVR device is used complete part number Target voltage and speed Clock source and fuse setting of the AVR Programming method ISP JTAG or specific Boot Loader Hardware revisions of
14. a LED the corresponding port pin must drive a low level Figure 2 7 LEDs Implementation schematic ME AASA LEDs i In line Grouped LEDs i ik nia i lt gt PD 7 0 Table 2 1 Leds references LED Reference AT90USB Connection Color D2 PORTD 4 Red PORTD 5 Green D5 PORTD 6 Green PORTD 7 Red The temperature sensor uses a thermistor R29 or temperature sensitive resistor This thermistor have a negative temperature coefficient NTC meaning the resistance goes up as temperature goes down Of all passive temperature measurement sensors thermistors have the highest sensitivity resistance change per degree of temperature change Thermistors do not have a linear temperature resistance curve The voltage over the NTC can be found using the A D converter connected to channel 0 See the AT90USB Datasheet for how to use the ADC The thermistor value RT is calculate with the following expression Rr Ry Kapen VCC Vanco Where RT Thermistor value Q at T temperature Kelvin RH Second resistor of the bridge 100 KQ 10 at 25 C Vanco Voltage value on ADC 0 input V VCC Board power supply A MEL AT90USBKey Hardware User Guide AT90USBKey Hardware User Guide Using the AT90USBKey The NTC thermistor used in AT9OUSBKey has a resistance of 100 KO 15 at 25 C To and a beta value of 4250 3 By the use of the following equation the temperature T can be calculated Wher
15. e T g B n7 r Rr Thermistor value Q at T temperature Kelvin B 4250 3 Ro 100 KO 45 at 25 C To 298 lt 273 K 25 The following cross table also can be used It is based on the above equation Table 2 2 Thermistor Values versus Temperature Temp RT Temp RT Temp RT Temp RT C KQ C KQ C KO C KQ 20 1263 757 10 212 958 40 50 486 70 15 396 19 1182 881 11 201 989 41 48 350 71 14 851 18 1107 756 12 191 657 42 46 316 72 14 329 17 1037 934 13 181 920 43 44 380 73 13 828 16 973 006 14 172 740 44 42 537 74 13 347 15 912 596 15 164 083 45 40 781 75 12 885 14 856 361 16 155 914 46 39 107 76 12 442 13 803 984 17 148 205 47 37 513 77 12 017 12 755 175 18 140 926 48 35 992 78 11 608 11 709 669 19 134 051 49 34 542 79 11 215 10 667 221 20 127 555 50 33 159 80 10 838 9 627 604 21 121 414 51 31 840 81 10 476 8 590 613 22 115 608 52 30 580 82 10 128 7 556 056 23 110 116 53 29 378 83 9 793 6 523 757 24 104 919 54 28 229 84 9 471 5 493 555 25 100 000 55 27 133 85 9 161 4 465 300 26 95 342 56 26 085 86 8 863 3 438 854 27 90 930 57 25 084 87 8 576 2 414 089 28 86 750 58 24 126 88 8 300 1 390 890 29 82 787 59 23 211 89 8 035 0 369 145 30 79 030 60 22 336 90 7 779 1 348 757 31 75 466 61 21 498 91 7 533 2 329 630 32 72 085 62 20 697 92 7 296 3 311 680 33 68 876 63 19 930 93 7 067 4 294 826 34 65 830 64
16. ecution after reset Refer to AT9OUSB datasheet section boot loader support To force bootloader execution operate as follow m Press both RST and HWB push buttons W First release the RST push button m Release the HWB push button For more information about the USB bootloader and Flip application please refer to the USB bootloader datasheet document and Flip s user manual Note The HWB pin is active only if the HWBE fuse is set default factory configuration 2 5 2 Programming with AVR JTAGICEmKII AT90USBKey Hardware User Guide The AT90USB can be programmed using specific JTAG link To use the AVR JTAGICEmkII with an AT9OUSBKey an optional HE10 connector should be soldered to J9 footprint Then the JTAG probe can be connected to the AT90USBKey as shown in Figure 2 10 Note When the JTAGEN Fuse is unprogrammed the four TAP pins are normal port pins and the TAP controller is in reset When programmed the input TAP signals are internally pulled high and the JTAG is enabled for Boundary scan and programming The AT90USB device is shipped with this fuse programmed AMEL 7627A AVR 04 06 Using the AT90USBKey Figure 2 10 Connecting AVR JTAG ICE to AVRUSBKey The Flash EEPROM and all Fuse and Lock Bit options ISP programmable can be programmed individually or with the sequential automatic programming option Note See AVR Studio on line Help for information 2 6 Debugging 2 6 1
17. ted on recycled paper 7627A AVR 04 06 xM
18. ver the VBUS pin of its USB mini AB connector A couple of transistors allows the UVCON pin of the AT90USB to control the VBUS generation See Figure 2 3 In this mode the AT90USBKey is powered by external battery power supply source Figure 2 3 VBUS generator schematic FDV304P FAI 5V gt TAL To R25 UVCON poset is 100k 2 2 3 POWER ON LED The POWER ON LED D1 is always lit when power is applied to AVRUSBKey regardless of the power supply source AT90USBKey Hardware User Guide AIMEL 2 7 7627A AVR 04 06 Using the AT90USBKey 2 3 Reset 2 3 1 Power on RESET 2 3 2 RESET Push Button 2 3 3 Main Clock XTAL 2 8 7627A AVR 04 06 Although the AT90USB has its on chip RESET circuitry c f AT9OUSB Datasheet section System Control and Reset the AVRUSBKey provides to the AT90USB a RESET signal witch can come from two different sources Figure 2 4 Reset Implementation R6 47k C8 220nF RESET RST The on board RC network acts as power on RESET By pressing the RESET push button on the AVRUSBKey a warm RESET of the AT90USB is performed To use the USB interface of the AT90USB the clock source should always be a crystal or external clock oscillator the internal 8MHz RC oscillator can not be used to operate with the USB interface Only the following crystal frequency allows proper USB operations 2MHz 4MHz 6MHz 8MHz 12MHz 16MHz The AT90USBKey comes with a default 8MHz crystal oscillator A M
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