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TMS320F28379D: Custom board with F28379D and external XDS100v2 from Spectrum Digital SCI-A serial port not working

Part Number: TMS320F28379D
Other Parts Discussed in Thread: LAUNCHXL-F28379D, , TMDSEMU110-U

ear all,

I have a Simulink model that I can build and load with a LAUNCHXL-F28379D with an on-board xds100v2, as well as, with a custom board with a TMS320F28379D and external XDS100v2 from Spectrum Digital, I use the same code in both cases. I do not have any issues with the JTAG pins in both cases. However, when I want to use the external mode from Simulink which uses SCI-A, I can connect with the LAUNCHXL-F28379D without any issues, setting the correct COM port and SCI-A pins GPIO42 and GPIO43, but not with the custom board with TMS320F28379D and external XDS100v2 which uses the same pins (I have solutions with pull-up resistors and without them in these pins, but nothing).

In the external XDS100v2 I have the XDS100 Class Auxiliary Port set as Virtual COM port to use it as serial port. I have concluded that this second port are the GPIO43/SCIARX(->MCU) and GPIO42/SCIATX(<-MCU) pins like in the LAUNCHXL-F28379D and should work exactly in the same way in my custom board solution. But the serial connection does not work, I do not see any attempt even to send a message.

I have also tried the same with a XDS110 debug probe, which I am able to build and load with my custom board, but the serial in the XDS110 Class Application/User UART does not work either.

Am I missing anything?

Regards,

Irma.

  • Hi Irma,

    In the external XDS100v2 I have the XDS100 Class Auxiliary Port set as Virtual COM port to use it as serial port. I have concluded that this second port are the GPIO43/SCIARX(->MCU) and GPIO42/SCIATX(<-MCU) pins like in the LAUNCHXL-F28379D and should work exactly in the same way in my custom board solution.

    How did you arrive at this conclusion? Per my understanding neither the 14-pin nor the 20-pin header on the SD XDS110v2 probe bring out the UART pins.

    I have also tried the same with a XDS110 debug probe, which I am able to build and load with my custom board, but the serial in the XDS110 Class Application/User UART does not work either.

    The UART pins come out on a different connector, separate from the JTAG connector (check the user guide for the XDS110 debug probe). Are you connecting to the right pins?

  • Hi Gus,

    I have seen the following question/answer in the FAQ of the XDS100v2, so I thought it was feasible. I see this second port but afterwards it does not work.

    Irma.

  • Hello Irma,

    Are you able to physically connect the FTDI Port B TX and RX pins on the XDS100v2 to the MCU SCI-A pin then? Sorry, I don't have this debug probe available, so I don't know if this is possible. 

    Were you able to get the XDS110 COM port working?

  • Hi Gus,

    I have pin 13 and pin 14 of the 14-pin JTAG connector connected to GPIO42 and GPIO43 of the F28379D, which are assigned as SCI-A Tx and SCI-A Rx, respectively.

    In the XDS100v2 debug probe I see XDS100 Class USB Serial Port, which is the Virtual COM Port of the XDS100 Class Auxiliary Port (Port B).

    In the XDS110 debug probe I also see both COM ports, the XDS110 Class Application/User UART and XDS110 Class Auxiliary Data Port. I want to use the User UART part.

    If I connect the LAUNCHXL-F28379D which has an on-board XDS100v2 I see the same ports and in this case the serial is working fine.

    I have reasigned several times de COM port numbers, but that's not it.

    Irma.

  • Irma,

    I have pin 13 and pin 14 of the 14-pin JTAG connector connected to GPIO42 and GPIO43 of the F28379D, which are assigned as SCI-A Tx and SCI-A Rx, respectively.

    Pins 13 and 14 on a standard 14-pin JTAG connector are assigned to EMU0/EMU1 function. Neither the XDS100v2 or XDS110 will support SCI/UART functionality on the 14-pin JTAG headers.

    For the Spectrum Digital XDS110v2, you can see the pinout of the 14-pin and 20-pin JTAG header on the schematic screengrab below. Given that this is a Spectrum Digital design (not TI design) I may not have the latest schematic files, but I'm fairly certain this COM feature is not supported anywhere on this debug probe.

    For the XDS110 debug probe (TMDSEMU110-U to be clear), you need to connect the MCU SCI pins to the AUX connector, see below.

  • Thank you very much Gus. The FAQ of the XDS100v2 mentioning the UART as well as the name assigned in the XDS110 to the debug probe (yes, the TMDSEMU110-U) XDS110 Class Application/User UART made me thought that this was possible. I must confess that this naming is confusing.