RadioLink + USB (TX/RX Mismatch)

Support Wixel
1

Hi,

I’ve modified the wireless_adc_tx and rx apps to (1) use RadioLink instead of RadioQueue and (2) transmit a set of 8-bit integers instead of the serial number. For some reason, the last integer output to the COM port does not match the value I set in the source code - i.e., txPacket[4] does not match rxPacket[4]. Every other value matches as expected, and I haven’t been able to parse out a pattern (setting it to “3” in tx results in “0” on the terminal, “23” → “0”, “4” → “2”, etc). Any troubleshooting tips would be helpful!

EDIT: Now, no matter the value of txPacket[4], the terminal output shows “03”.

TX CODE

void adcToRadioService()
{
    static uint16 lastTx = 0;

    uint8 XDATA * txPacket;

    // Check to see if it is time to send a report and
    // if there is a radio TX buffer available.
    if ((uint16)(getMs() - lastTx) >= param_report_period_ms && (txPacket = radioLinkTxCurrentPacket()))
    {
        // Both of those conditions are true, so send a report.

        uint8 i;
        uint16 XDATA * ptr = (uint16 XDATA *)&txPacket[5];

        // This should be done before all the ADC readings, which take about 3 ms.
        lastTx = getMs();

        // Byte 0 is the length.
        txPacket[0] = 16;

        // Bytes 1-4 are the serial number. MODIFIED
        txPacket[1] = 1;
        txPacket[2] = 2;
        txPacket[3] = 3;
        txPacket[4] = 4; //TERMINAL OUTPUT (RX CODE) NEVER MATCHES THIS VALUE

        adcSetMillivoltCalibration(adcReadVddMillivolts());

        // Bytes 5-16 are the ADC readings on channels 0-6.        
        for (i = 0; i < 6; i++)
        {
            *(ptr++) = adcConvertToMillivolts(adcRead(i));
        }

        radioLinkTxSendPacket(0);
    }
}

RX CODE

void radioToUsbService()
{
    uint8 XDATA * rxPacket;


    // Check if there is a radio packet to report and space in the
    // USB TX buffers to report it.
    if ((rxPacket = (uint8 XDATA *)radioLinkRxCurrentPacket()) && usbComTxAvailable() >= 64)
    {
        // We received a packet from a Wixel, presumably one running
        // the wireless_adc_tx app.  Format it nicely and send it to
        // the USB host (PC).

        uint8 i;
        uint16 XDATA * ptr_16bit = (uint16 XDATA *)&rxPacket[5];

        printf("%02d-%02d-%02d-%02d-%02d %5u",
         rxPacket[0],
         rxPacket[1],
         rxPacket[2],
         rxPacket[3], 
         rxPacket[4], //THIS VALUE IS NOT MATCHING txPacket[4] IN THE TX CODE
         (uint16)getMs()
         );

        for(i = 0; i < 6; i++)
        {
            printf(" %5u", *(ptr_16bit++));
        }

        putchar('\r');
        putchar('\n');

        radioLinkRxDoneWithPacket();
    }
}

TERMINAL OUTPUT

41%20PM
41%20PM404×706 29.2 KB

2

Hello.

I am sorry you are having trouble with the Wixel. I do not see any issues in the code you posted. Could you post the complete code for both the transmitter and the receiver here? If I don’t notice anything wrong in the code, I’d like to try running the code on two Wixels here to see if I can reproduce the problem. What versions of the Wixel SDK and SDCC are you using? What operating system are you running on the machine that compiles the code?

–David

3

Hi David,

Seems like it was a hardware issue (specifically the USB cable) - unsure about why exactly, but everything works as expected now. I can still post the code if you’d like. Thanks!