SoftRock RXTX Ensemble USB Interface
Contents
1. o CW2 low J PEOFKO Config SoftRock V9 0 Si570 General USB Si570 LO Tune ABPF Calibrate Test Mobo About Information Crystal frequenty 114 285000 MHz Startup 28 200000 MHz LO Calculation Si570 Registers C Dividers H Smoothtune 3500 ppm RFREQ 48 GHz 5 67 Calc frequenty DCO 5 0 GHz Read frequenty 28 200000 h 6 3 V mi PI PTT p P2 CWw1 m Cw2 Repeat William R Robinson Jr AJ4MC pl0of 12 2011 All rights Reserved William R Robinson Jr o Note time to turn on PTT is about 6 uSec SoftRock RXTX Ensemble USB Interface PTT ISOLATION PTT using PowerSDR IQ v 1 12 20 Tune button o Magenta PB4 after R11 on U4 1 o Green PTT on U4 4 Bn 25 52 L tm mm i 30 008 s l M2 5u CHS EDGE 7 CHi 5 mU CH2 5 0m CH3 1V lt 2 Hz CH4 20 AJ4MC 2011 All rights Reserved pllof 12 SoftRock RXTX Ensemble USB Interface References 1 Robson Richard R Sr WBSRVZ Ensemble RXTX Project http www wb5rvz com sdr ensemble index htm online accessed 2011 2 Dick Streeland USBtiny http www xs4all nl dicks avr usbtiny online accessed 2011 3 UNKNOWN USB Overview http en wikipedia org wiki USB USB_ 1 0 online accessed 2011 4 ATMEL 8 bit Microcontroller with 2 4 8K Bytes In System Programmable Flash http www farnell com datasheets 3892 pdf online accessed 2011 5 NXP Phil2. 77216 8 388608000000 1000008 16777224 8 388607805696 1000011 16777233 8 3886081 11392 1000019 16777241 8 388607917088 1000022 16777250 8 388608222784 100002A 16777258 8 388608028480 1000032 16777266 8 388607834177 100003b 16777275 8 3886081 39872 1000043 16777283 8 388607945568 100004b 16777291 8 388607751265 1000054 16777300 8 388608056960 10000A8 16777384 8 388608113919 10000FC 16777468 8 388608170877 1000150 16777552 8 388608227835 William R Robinson Jr AJ4MC p7of 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface 10001a3 16777635 8 388607784805 10001F7 16777719 8 388607841765 100024B 16777803 8 388607898724 100029F 16777887 8 388607955682 10002F3 16777971 8 388608012639 1000347 16778055 8 388608069597 100039B 16778139 8 388608126553 0F000000 251658240 0F800000 260046848 8 388608000000 10000000 268435456 8 388608000000 10800000 276824064 8 388608000000 11000000 285212672 8 388608000000 11800000 293601280 8 388608000000 12000000 301989888 8 388608000000 12800000 310378496 8 388608000000 13000000 318767104 8 388608000000 13800000 327155712 8 388608000000 14000000 335544320 8 388608000000 o It appears that the value sent is the requested frequency 8 3886080 o I also noted that 2 raised to the 23 0x800000 is equal to 8388608 decimal o Ido not know of any reason for this ratio other than to speculate it is useful for the firmware inside the ATTiny85 o I posted this question to the softrock40 Interest g
3. SoftRock RXTX Ensemble USB Interface 3 3V To Quad Clock 2T bifilar of 30 2x4 in BN 43 24 2 core To U4 LTV 817 cs2 8 1454 c51 1454 Qi 2N3986 Paddles 1 Reference Purpose and Function The USB interface provides a way for the PC running SDR Software Defined Radio software to control the local oscillator and PTT functions The transceiver is controlled by an Attiny85 microcontroller programmed as a USB device to provide PTT control paddles input and local oscillator frequency control in a galvanically isolated area of the PCB Theory and Design e This is areally neat design for USB using only a small microprocessor and a handful of parts e Speed is USB 1 0 at 1 5 Mbits sec which would seem to slow but it is only used for control the Rx and Tx data is not passed through the USB bus but instead is passed as analog stereo to and from the PC sound card Only Local Oscillator frequency selection CW1 CW2 and PTT control signals are passed across the USB interface e The assembly manual provides credit and a link to PEOFKO for the firmware and links to his website at http home ict nl fredkrom peOfko SR V9 i570 index shtml install e That web page states the firmware is based on the free USB AVR CODE by DG8SAQand links to http www obdev at products vusb index html e Under Links this web page refers to http www xs4all nl dicks avr usbtiny where the following description of this circu
4. ds little or no delay age 2 Feb 11 21 26 Trig M H E sve 7 aH Veme be eeeteeeeteeee EE EN TR PE ee 4 or h 13 19 60us MAIN ou BECHS EDGE X lt 2aHz CHI S 0mU CH2 5 mU CH3 2V CH4 2U CW2 INPUT SDA out e CFGSR software does not prevent the simultaneous use of PB 1 for I2C and CW2 o In fact this often lead to the USB being Disconnected by the PC e The trace below shows the key being closed during an I2C communications o It appears that the I2C may be attempting to drive high the SDA line instead of letting the pull up resistor bring the line high e Keying on CW2 interrupting I2C o Magenta J2 2 o Green PB1 ogo _92 Feb 11 21 19 Trig pH Ta ne um mci EDGE X lt 2 Hz cM 5 0m CH2 5 m CH3 2V CH4 2U William R Robinson Jr AJ4MC p9of 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface e The screen shots below show that the 51570 registers are not readable during when CW2 is low o CW2 high PEOFKO Config SoftRock V9 0 Si570 General USB 5i570 LO Tune ABPF Calibrate Test Mobo About Information Crystal frequenty 114 285000 MHz Startup 28 200000 MHz LO Calculation Si570 Registers Dividers HS_DIV 11 N1 16 Smooth tune 3500 ppm RFREQ 43 428271145 485 GHz 5 67 Calc frequenty 28 200000 MHz DCO 5 0 GHz Read frequenty m PI PTT m P2 CwW1 m
5. ext packet can be received while the current one is being processed Depending on the packet type a reply packed may be sent back immediately in the interrupt handler USB CONTROL e The 3 3V zener diodes D1 and D2 are used to reduce the 5 volt outputs from the ATTiny85 to 3 3 volts This complies with the USB requirement of a high being between 2 8 and 3 6 Volts 3 e The 68 ohm resistors R1 and R2 limit the current into the ATTiny85 o 5 3 3V 68 ohms 25 mA o The ATTiny85 has a maximum of 40 mA for each I O with a 60 mA total 40166 7 e R5is used to pull up D to signal to the host PC that the device that this is a low speed device Normally this is done with a 1 5K resistor to 3 3V However in this case it is pulled up to SV o Current with 3 3V across a 1 5Kohm resistor 3 3V 1 5K 2 2 mA o Resistor for same current pulled up to SV R 5V 2 2mA 2 27K R5 and R2 both limit the current and add up to 2 268 ohms well within 5 resistor tolerance e R6 provides a weak Pullup on D perhaps it for when the USB is not pulled in I am not sure if this part is really needed o I detected no failures using CFGSR software with R6 removed e C50 is just a bulk capacitor for the USB 5V power supply to the ATTiny85 e ATTiny85 PB1 is used as a bidirectional I O for the IC SDA line e ATTiny85 PB3 is used as a bidirectional I O for the PC SDC line e R10 and R9 provide the required pull up resistors required by the I2C protocol The ATTin
6. itry is found USBtiny is a software implementation of the USB low speed protocol for the Atmel ATtiny microcontrollers Of course it will also work on the ATmega series The software is written for an William R Robinson Jr AJ4MC plof 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface AVR clocked at 12 MHz At this frequency each bit on the USB bus takes 8 clock cycles and with a lot of trickery it is possible to decode and encode the USB waveforms by software The USB driver needs approximately 1250 to 1350 bytes of flash space excluding the optional identification strings depending on the configuration and compiler version and 46 bytes RAM excluding stack space The C interface consists of 3 to 5 functions depending on the configuration USB uses two differential data signals D and D which are normally complementary However the end of a packet is signalled by pulling both signals low Data is not transmitted directly on the USB bus it is NRZI encoded first This means that a 0 bit is encoded as a bit change and a 1 bit is encoded as no bit change After 6 1 bits bit stuffing takes place to force a change on the USB signal lines The software is interrupt driven the start of a USB packet triggers an interrupt The interrupt handler synchronizes with the sync byte removes the NRZI encoding and bit stuffing and stores the packed in one of the two RAM buffers Two buffers are used so that the n
7. lips UM10204 I2C bus specification and user manual Rev 03 19 June 2007 http www nxp com documents user manual UM 10204 pdf p8 online accessed 2011 6 LITEON High Density MountingType Photocoupler LTV 817 series http www us liteon com downloads LTV 817 827 847 PDF p12 112 online accessed 2011 William R Robinson Jr AJ4MC pl2of 12 2011 All rights Reserved
8. obinson Jr AJ4MC p5of 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface e With HUB o Top D o BOT D oa 2 Feb 11 20 45 BROR f eeteeeetee SJ 4 om re vi ME a MAIN B2 5us Bohs EDGE Z 565 979Hz CH1 500mY CH2 5 ml CH3 1 CH4 1U e With PC o Top D o BOT D Il 3 4 pl ba WV U b MAIN 2 5us BCH4 EDGE Z 292 189Hz CH1 50 mY CH2 S5 m CH3 1 CH4 10 William R Robinson Jr AJ4MC p6of 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface USB PAYLOADS e A USB traffic analyzer was used to study the traffic across the USB interface between the PC and the ATTiny85 o A screen shoot from the tool is shown below Untitled Ellisys Visual USB Joe File View Search Record Help oY GG lt v s a q Item Device End I Status S Payload Time Details ax HE FE vm gr Y Y EE keep Alive 2 497 sanon Vendor request OUT 0x32 EQ Vendor request OUT 0x32 1 0 OK 4 bytes 00 00 00 OF 2 496 163 E Keep Alive 608 2 497 155 JJ Vendor requests are not decoded Bq Vendor request OUT 0x32 1 o oK 4 bytes 00 00 80 OF 3 104 201 piece open ie element aniren D E Keep Alive 472 3 105 192 SETUP transaction to find out more Vendor request OUT 0x32 1 0 OK ws 4 bytes 00 00 00 10 3 576 230 ere eee F R Keep Alive 392 3 577 222 Vendor request OUT 0x32 1 0 OK 4 byte
9. roup have not received any replies http groups yahoo com group softrock40 52262 USB Data Packets Format Jan 28 2011 6 36 pm LC e Below is a logic trace of the ATTiny85 accessing the S1570 Write to address 55 Note that clock stretching is very evident The byte takes about 145 usec for a rate of about 55 Kbits sec H Intronix LogicPort Logic Analyzer C Program Files LogicPort Projects Quickstart LPF BAX File Options Setup Acquisition View Help Waveforms State List Notes g D amp hk gt gt a Tl k gt Q Q Q Q Bulfer Position street a Sample Rate vi 10mHz vi Logic Threshold v 1 80v Pre Trigger Buffer vil 1 Measurement A Source v CLKT vi 4 gt lt I gt l gt i 4 1 Signal Wire 100us 80us 60us Aus 20us T 111us 20us 4Qus 60us 80us 100us x Mk c NEED EE 22 Lo ee CT PRESS dk f FEL VA ETE SEN EE ee eS SDA DO SEL D1 12C W 55h Ya a4 2 Prefill complete Waiting for trigger Acquisition 4 Samples 5 23M CLK1 Freq OH2 CLK1 Cycles A gt B 0 Rate A gt B 2MHz Width CLK2 A gt T N A William R Robinson Jr AJ4MC p80f 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface e The trace below shows the keyin on J2 5 and input to the ATTiny85 on PBS o Magenta J2 5 o Green PB5 o Note R8 ad
10. s 00 00 80 10 3 968 254 F R Keep Alive 344 3 969 246 F g Vendor request OUT 0x32 1 0 OK 4 bytes 00 00 00 11 4 312 276 H Keep Alive 328 4 313 267 E Vendor request OUT 0x32 1 o OK 4bytes 00 00 80 11 4 640 296 F R Keep Alive 328 4 641 287 Vendor request OUT 0x32 1 0 OK ws 4bytes 00 00 00 12 4 968 316 F R Keep Alive 345 4 969 307 Vendor request OUT 0x32 1 0 OK 4 bytes 00 00 80 12 5 313 337 Keep Alive 312 5 314 329 Eg Vendor request OUT 0x32 1 0 OK ws 4 bytes 00 00 00 13 5 624 357 4 a Keep Alive 313 5 624 457 l Details J Search P Export Summary E Vendor request OUT 0x32 1 0 OK 4 bytes 00 00 80 13 5 936 376 Data ax L Keep Alive 305 5 937 367 DEP 03254 Vendor request OUT 0x32 1 0 OK s 4 bytes 00 00 00 14 6 240 394 0x0000 00 00 00 OF 43 Keep Alive 2 416 6 241 386 2 APPEND New elements append 9 656 536 H Keep Alive 1 973 9 656 536 Eg Vendor request OUT 0x32 1 0 OK 4 bytes 00 00 00 OF 11 628 66 t Keep Alive 1 840 11 629 65 p Bookmarks I Devices amp Setup amp Data Ready 3 3 3883 0 27 elements displayed CAP NUM o The table below shows some of the frequency vales that were requested using CFGSR software and the values sent across the interface Requested Packet Packet value Frequency Payload Dec packet Requesed Frequency 1000000 167
11. s Reserved SoftRock RXTX Ensemble USB Interface Calculated e NONE Simulation e NONE William R Robinson Jr AJ4MC p4of 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface Real Circuit USB CONTROL e The Trace below shows the zener diodes keeping the D output back to the PC at 3 3 Volts e The pulses on the left side are from the ATTiny to the PC o D is at the zenor voltage of 3 3 Volts o PB2 is about 180 mV higher than D due to the voltage drop across the 68 ohm R2 e The pulses on the right are from the PC to the ATTiny85 o D is higher than the zenor voltage of 3 3 Volts suggesting that the PC has significant drive power o PB2is about 110 mV higher than D due to the voltage drop across the 68 ohm R2 o The voltage drop across the 68 ohm resistor is less as little current goes into PB2 when it is an input then comes out when it is an output what little current that does flow is more likely through the 2 2K R5 e How zenors and 68 ohm resistors do voltage conversion o Magenta D o Green PB2 _ me Be feb ll 20 36 S MM gt H 6 PEER STE SE ha ari BREE re EE eres tri MAIN Bius BCHS EDGE JY 589 15 Hz CH 300mU CH2 5 m CH3 1U CH4 14 e The two traces below show the changes when connected to the PC directly verses using a USB hub Changing from PC USB port to USB HUB changes voltages on the right side only suggesting the right side is from the PC to the ATTiny William R R
12. y85 I O are tri stateable so can emulate the required Open drain behavior William R Robinson Jr AJ4MC p2of 12 2011 All rights Reserved SoftRock RXTX Ensemble USB Interface CW1 INPUT e CWI comes from J2 5 and goes to Ul 1 PB5 The input is active low e R3 provides a pull up resistor so the input does not float when the key paddles are not connected or open e R8 limits the current into out of the ATTiny85 below the required o When the J2 5 is floating the current from the SV supply and into the ATTiny85 is o 1 5V 4 7K 4 7K or 0 5 mA When the J2 5 is closed to ground the current from the 5V supply is o 1I 5V 4 7K or 1 0 mA o CW2 INPUT SDA out e THE ATTiny85 PB1 Is used for two purposes It is used as an output along with PB3 to control the Local Oscillator Frequency and it is use as an input for CW2 from J2 2 e This is compatible because conceptually the user would not want to be transmitting while adjusting the output frequency e Both I2C and the paddles use a pull up resistor for High values so it is not obvious to me why R4 R7 and Q1 are required PTT ISOLATION e U4 provides opto isolation from the USB power and the rest of the card e R11 limits the current to the LED in U4 Th opto isolator has a Forward voltage of 1 2V minimum and a max forward current of 20mA o Rilmin 5 1 2 V 20mA 190 ohms o So 470 ohms is well within the requirements William R Robinson Jr AJ4MC p3of 12 2011 All right
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