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UART issue on the C6713

Michael Gillett
Prodigy 10 points
Other Parts Discussed in Thread: MAX232

Hello, I am a final year student in the UK trying to get the TMS320C6713 DSP to interface with a touchscreen via a UART connection. I am using the DSK from Spectrum Digital and CCS 3.1. I am using SPRA633C document to get the serial port on the DSK to act like a UART. I have connected pin 36, 42 and 44 and DX1, DR1 and GND respectively on the J3 serial port. These pins connect to a MAX232 chip which itself connects to a PC. I want to test the output of the DSP before connecting it to the touchscreen but currently I am just trying to get the tutorial code to work.

I have tried using software to send characters from the PC to the DSP and back as the tutorial describes but so far I have not been able too. I have consulted a PhD student at my university who is researching DSPs and has worked with the C6713 before but he was unable to offer any help with why it wont work. I have noticed that in the SPRA633C document figure 14 on page 11 appears to have an error. From other documents I have seen it appears that the CONN DB9 connection is incorrectly labeled; pin 9 is shown as GND in SPRA633C when in other documents GND should actually be 5.

If anyone can offer any advice or help it would be greatly appreciated as I need to get this working by the end of the week.

Thanks in advance, Michael

 

  • 0
    TI__Guru* 84110 points

    Michael Gillett said:
    I need to get this working by the end of the week.

    We are apparently too late to help. Did you find success in your own debug process?

    Michael Gillett said:
    SPRA633C document figure 14 on page 11 appears to have an error. From other documents I have seen it appears that the CONN DB9 connection is incorrectly labeled; pin 9 is shown as GND in SPRA633C when in other documents GND should actually be 5.

    This would be surprising to have such an error in a standard connector for a long-term standard like RS232. Could it be that both pins are GND on a fully-implemented DB9? If you have found out anymore about this, please pass it on.

    Michael Gillett said:
    I am using SPRA633C document to get the serial port on the DSK to act like a UART.

    This app note has been used successfully for many years. Although I did not confirm your specifics, you seem to have a good understanding of what you are doing and how to do it. My suggestions, if they had not come too late, would have been in the area of debugging potential issues with your system. Starting from the PC, I would look at the serial port signals at the then of the PC's cable, then through the MAX232, then look at them as close to the DSP's RX1 pin as possible. Then start looking at the DSP's operation using CCS 3.1. You can look at the McBSP registers to see if any response is getting in and look to see what data might be in the data-in register DRR (this can be tricky sometimes since reading it with CCS might also make the McBSP think it has been read by DSP code, just something to keep in mind).

    Did you have any good fortune this week and solved your problems and got your project running? Please let us know, and please know that there are many of us who are sad that we did not get a quicker response to your post.

    Regards,
    RandyP