SkyTraq Venus 6 EVK/SDK (Home)

Trivia:

The Venus634/638 uses the Sparc v8 compatible LEON2 CPU (free IP-core by Aeroflex Gaisler).
The LEON2 inside the Venus638 runs with 50 MHz, the internal peripherals (e.g. SPI, I2C) with 15.003694 MHz.
The PIOs are I/Os from the LEON2 design, the GPIOs are additional peripheral I/Os.
A bricked Venus638 FLASH can be reprogrammed by booting the chip from ROM (JP3 2-3), download a prom.bin with the GPS-Viewer and restart the chip from FLASH (JP3 1-2).

Worth knowing:

The SDK works also with the sparc-elf-3.4.4-1.0.33 toolchain, on Windows and Linux
(sparc-elf-3.4.4-1.0.33-mingw and sparc-elf-3.4.4-1.0.33-linux).
Be aware, that SkyTraq maybe will refuse support if you do not use the suggested v1.0.31b toolchain!!
Gaisler toolchains above v1.0.33 will compile the sources, but the binary will not work on the Venus63x!

A lightweight and fast compiling environment (about 30MB HDD space) can be set up as an alternative to the Cygwin installation suggested by SkyTraq (be aware, that SkyTraq maybe will refuse support if you do not use the suggested Cygwin-environment!!):

Create a directory "C:\opt"
Unzip the sparc-elf-toolchain to "C:\opt" to get the following structure
"C:\opt\sparc-elf-3.4.4-mingw\..."
Unzip the SDK to "C:\opt" to get the following structure "C:\opt\STI_GPS\..."
Download the GnuWin32 "Core-Utilities".
The Core-Utilities contains the missing helper binaries.
Start the installer. Set the installation directory to "C:\opt\GnuWin32".
Add the following pathes to your PATH environmental variable:
C:\opt\sparc-elf-3.4.4-mingw\bin;C:\opt\GnuWin32\bin

Finaly the directory structure should look like this simplified tree:

    C:\
    +---opt
        +---SDK.pdf
        +---STI_GPS
        |   +---obj
        |   +---lib
        |   +---dep
        |   \---bin
        +---sparc-elf-3.4.4-mingw
        |   +...
        |   \...
        \---GnuWin32
            +...
            \...

To test the installation change directory to "C:\opt\STI_GPS\" and type:

    C:\opt\STI_GPS>make clean
	
    The result should be:
    rm -f obj/* dep/* bin/*
    
    C:\opt\STI_GPS>make
	
    The result should be similar to that:
    sparc-elf-gcc -MMD -MG -Wall -c -g -DNDEBUG -funswitch-loops -fweb -frename-regi
    sters -mv8 -msoft-float -I../kernel/inc main.c
    sparc-elf-gcc -MMD -MG -Wall -c -g -DNDEBUG -funswitch-loops -fweb -frename-regi
    sters -mv8 -msoft-float -I../kernel/inc spi.c
    sparc-elf-gcc -MMD -MG -Wall -c -g -DNDEBUG -funswitch-loops -fweb -frename-regi
    sters -mv8 -msoft-float -I../kernel/inc nmea.c
    sparc-elf-gcc -MMD -MG -Wall -c -g -DNDEBUG -funswitch-loops -fweb -frename-regi
    sters -mv8 -msoft-float -I../kernel/inc uart_intf.c
    sparc-elf-gcc  obj/*.o lib/*.o lib/kernel.lib -mv8 -msoft-float -Ttext=0x4000000
    0 -lm  -o bin/soc
    sparc-elf-mkprom -Tdata=0x60000000 -freq 50 -rmw -romws 5 -ramwidth 16 -ramrws 3
     -ramwws 3 -stack 0x60013fe0 -baud 38400 -msoft-float -mv8 obj/main.o obj/spi.o
    obj/nmea.o obj/uart_intf.o lib/gps_main.o lib/uart.o lib/binmsg.o lib/pll_clock.
    o lib/flash.o lib/lte_flash.o lib/logdata.o lib/set_system.o lib/kernel.lib

    LEON MKPROM prom builder for BCC v1.0.29c
    Copyright Gaisler Research 2004, all rights reserved.

    Section in rom detected, switching off compression
    :
    :
    creating LEON3 boot prom: prom.out
           1 Datei(en) kopiert.

    mv prom.out bin
    sparc-elf-objcopy -O binary bin/prom.out bin/prom.bin
    sparc-elf-objdump -d -S bin/prom.out > bin/prom.asm
    rm -f tmp.out
    rm -f bin/prom.out

For a detailed information about the prom.bin, download the MinGW "GNU-Binutils".
Extract "size.exe" from the downloaded file (e.g. with 7-zip v9.20) and copy it to
"C:\opt\GnuWin32\bin".

Now you can add the following (blue) lines to your "Makefile":

    :
    $(LD)  $(OBJ_DIR)...
    $(MKPROM) -Tdata=0x6...
    size prom.out
    sparc-elf-readelf -a prom.out >> prom.map
    mv prom.out $(BIN_DIR)
    mv prom.map $(BIN_DIR)
    sparc-elf-objcopy -O binary $(BIN_DIR)/prom.out $(BIN_DIR)/prom.bin
    sparc-elf-objdump -d -S $(BIN_DIR)/prom.out > $(BIN_DIR)/prom.asm
    rm -f tmp.out
    rm -f $(BIN_DIR)/prom.out
    :

Now "\bin\prom.map" contains the mapping information of all the variables of your code.

"BMSG_UserDefine is called by SkyTraq software which will process user defined binary message (following AN003 spec). Refer to the attached example.c file, I have used 2 examples inside the BMSG_UserDefine The first one is similar to SkyTraq query software version, except the request ID and response ID are different. The second is the set function which set the one GPIO data to be high or low."
(SkyTraq engineers answer and example code)

    U08 BMSG_user_reply_sw_version(U08 *buf, U08 *repbuf)
    {
        U08 retVal = FALSE
        
        if ( buf[0] == 1 )
        {
            U08 ndx = 1;    // reserve ndx=0 for internal assigned reply id
            retVal  = TRUE;
            
            repbuf[ndx++] = buf[0];

            repbuf[ndx++] =      0;
            repbuf[ndx++] = (U08)1;
            repbuf[ndx++] = (U08)2;
            repbuf[ndx++] = (U08)3;
            repbuf[ndx++] =      0;
            repbuf[ndx++] = (U08)4;
            repbuf[ndx++] = (U08)5;
            repbuf[ndx++] = (U08)6;
            repbuf[ndx++] =      0;
            repbuf[ndx++] = (U08)7;
            repbuf[ndx++] = (U08)8;
            repbuf[ndx]   = (U08)9;
        }

    return retVal;
    }

    U08 BMSG_user_configure_gpio(U08 *buf, U08 *repbuf)
    {
        U08 gpio_num = buf[0];
        U08 data     = buf[1];
        
        if ( data == 1 )
            gpio_high(gpio_num);
        else
            gpio_low(gpio_num);
    
    return TRUE;
    }
    
    //currently 0x51~0x6F, 0x95~0xa7, 0xf2~0xff are not used, others are used internally
    #define USER_QUERY_SW_VERSION_ID 0x51
    #define USER_REPLY_SW_VERSION_ID 0x95
    #define USER_SET_GPIO 0x52
    
    U08 BMSG_UserDefine(U08 reqID,U08 *reqbuf,U08 *repID,U08 *repbuf,U16 *replen)
    {
        U08 retval = FALSE;
        *repID = 0;
        *replen = 0;
        
        switch(reqID)
        {
            // example: set and need to reply
            case USER_QUERY_SW_VERSION_ID: 
                retval  = BMSG_user_reply_sw_version(reqbuf, repbuf);
                *replen = 14;   //this is the same format as the skytraq query sw version
                *repID  = USER_REPLY_SW_VERSION_ID;
                break;
            
            // example: set only
            case USER_SET_GPIO:
                retval = BMSG_user_configure_gpio(reqbuf, repbuf);
                break;  
        }
        return retval;
    }

"The process_nmea_message is called by process_kernel_output_data API. Without process_nmea_message, compile will fail. In process_nmea_message, we open NMEA_gga, NMEA_gll, NMEA_gsa, NMEA_gsv, NMEA_rmc, NMEA_vtg in nmea.c for user to change the output format of each message." (SkyTraq engineers answer)
"gps_process()" has to be called cyclically inside the main loop, otherwise, the chips watchdog will do a system reset after about 60s.
UART functions must not be used before calling "gps_init()", otherwise the CPU will hang.
The Venus638 uses the "SPI master core" from Opencores.org.
The SPI can run with a maximum of about 7.5 MHz (periph. bus frequency / 2).
If the SPI-master is used, PIO5 acts as alternative function SS #2 of the SPI. The pin can not be used as a GPIO in this case.
A Yamaichi "FPS009-3202-BL" SD-card socket fits the pads on the bottom of the Venus638-EVK.
For a proper operation of a SD-card, the MISO (pin 7 of the card socket) must be pulled to VCC33 with about 10k.
The Venus638 uses the "I2C controller core" from Opencores.org.
The I2C core can only be used in polling mode (polling "TIP", no IRQ).
The file "almanac.log" from the SkyTraq-FTP contains an actual "almarray[]" for the SDK.
To always have the latest almanac data included automatically in your sources, the following steps must be done:
If you are using the environment described above, download the GnuWin32 "Wget" package and install it as suggested to "c:\opt\GnuWin32".
The following (marked blue) has to be added to the "Makefile":
```
    :
    main.o: main.c almanac.log
    
    almanac.log:
        wget ftp://skytraq:skytraq@60.250.205.31/ephemeris/almanac.log
    
    $(BIN_DIR)/$(PRJ_NAME): $(system_objects)
    :
    :
    clean: 
        -rm -f obj/* dep/* bin/* almanac.log
    :
```
Additionally the "almanac.log" must be included into the "main.c" (marked blue):
```
    :
    U32 odm_revision;
    U32 odm_version = 0x010101;
    
    #include "almanac.log"
    
    S16 GGA_count = 0,...
    :
```
So if "alamanac.log" doesn't exist (e.g. after a "make clean"), the file is automatically downloaded at a "make". (Thanks to tz for that information and approach)

Introduction

Trivia and worth knowing things