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Piccolo sci communications not working - wrong sequence on computer

Steve Hofmeyr
Prodigy 30 points
Other Parts Discussed in Thread: CONTROLSUITE

Hi guys

I've recently started developing on Embedded Systems, and i'm having issues with the Piccolo. I'm using the standard 2082x example (C:\TI\controlSUITE\device_support\f2802x\v127\DSP2802x_examples_ccsv4\sci_echoback), but when i connect it up and run it, i don't receive the right comms on the other side (i use docklight). I've modified the above example to repetitively send a character (code below), but to no avail. Has anyone had this issue before, or am i doing something really stupid. I'm not sure what you may need to help out, most if it is the generic example...

I've wired it up in UART fashion Tx(piccolo)->Rx(pc) and vice versa, and gnd->gnd. I do also have a usb->serial converter, but the serial port built onto my motherboard gives the same issue

 

for(;;) {

scia_xmit(0x7E);

}

///   The above prints out 0x03 in docklight  repeatedly

Thanks

  • 0
    TI__Intellectual 3000 points

    Steve,

    What is your baud rate? Does the PC baudrate match the baudrate configured in the program? If they do match, check the schematic for the controlCARD to make sure switches are in the right positions.

    Nishant

  • 0 in reply to Nishant Garg
    Prodigy 30 points

    Hi Nishant

    It's set at the default 9600, as with the StopBits=1, Parity = None,  /No.Of bits sending = 8.

    And this is the piccolo control stick, the one the size of a flash drive (not the control card)... Any other ideas? i've been going as far as thinking it's a driver issue on my pc side.

    I have also just hooked up another piccolo, and the SCI communication works fine between the 2. But being new to Serial comms. i was under the impression that i could also interface it with my PC.

    Thanks,
    Steve

  • 0 in reply to Steve Hofmeyr
    TI__Intellectual 3000 points

    Steve,

    I ran the program directly from controlSUITE on a development kit with Piccolo A without any modifications. When you run the program hooked up to a PC, do you see the welcome message that says "Hello World!"? That would make sure you are at least connected through SCI.

    Have you configured your PC terminal for the right COM port for communication? You can check this on the device manager (Right click My Computer, properties, go to hardware tab). Also, make sure the flow control setting is "None" when you set the baud rate on your PC.

    Hope this helps.

    Nishant

  • 0 in reply to Nishant Garg
    Prodigy 30 points

    Hi

    No, thats the part that gets all scrambled, thats why i sent a repetitve sequence(the code in my first post)  i.e. 0x55 (which actually seemed to work) but then when i sent other codes through it came different on the PC. I.e. I sent 0xFD and 0x23 came out at the PC. But when i sent a different signal it came out with something else that in turn did not appear to have a linear relationship

    I spent about 2 days playing with the settings and pouring over your datasheet, to no avail. I'm pretty sure all the settings where as specified, i've checked them so many times.

    I've also downed the Baud rate, to say 2400, also didn't work.

    Has anyone else had a similar issue like this before?

    I'll also be able to get my hands on an Oscilloscope in a few days, so i'll report back if i find anything strange in the sent signal.

    Anyways, this isn't completely necessary for my current project, just needed for testing, so a solution isn't critical. My main aim, was to connect 2 Piccolo's, which works.

     

    Steve

  • 0 in reply to Steve Hofmeyr
    Mastermind 7585 points

    Steve,

    how did you connect the Piccolo stick to the PC?  If I remember the stick schematics right, there is no RS232 driver circuit at the stick. The PC -COM however expects RS232 voltage level at Rx and send this level at TX (which will probably damage the stick if connected directly) . 

    What GPIO Pins did you use for your SCI-test?  At the stick the pins GPIO28 and 29 (SCIA Rx and Tx) are hard wired to the FTDI chip to use the FTDI as an "Serial to USB" bridge.

    Regards