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Uart echo example for CC2650 sensor tag

Mohamad K
Intellectual 750 points
Other Parts Discussed in Thread: CC2650, MAX3232

Hi everybody

I am using a TI cc2650 sensortag (hardware ver 1.2), CC DevPack Debug and CCS v6.1. I wanted to check the uart echo example on my device. I used pin9 on DevPack as TXD, and pin11 as RXD but the board is completely silent and I didn't receive any echo. I switch pins and nothing happens. Then I tried different baud rates (9600 and 115200 included) still nothing. then I changed the code to send a constant character (0x55) on the line and use an oscilloscope to probe the line but still I saw a constant voltage.

I would really appreciate if someone helps me on this.

Note. I use a max3232 for voltage conversion between board and PC.

  • 0
    TI__Guru** 105180 points
    Hi,

    Did you step into the driver to see if there are any errors? Do you get any error return codes?

    Best wishes
  • 0 in reply to JXS
    Intellectual 750 points
    Hi
    Its been a while and I accidentally saw sth related to this, so i decided to share.

    In the board.c UART part, it passes "Board_EB_UART_TX" and "Board_EB_UART_RX" to UART pins. this pins work with SRF06EB.
    If one uses DebugPack (like me) he should change the pins to "Board_DP5_UARTTX" and "Board_DP4_UARTRX".
    Also in BoardGpioInitTable the "Board_DP5_UARTTX" pin defined as input and it should be changed to output.

    After the above changes I could saw the transmitted data with an oscilloscope, and the data and baud rate were OK. But I cant receive them on PC since the amplitude of pulses were less than 1V!!!! The drive strength is set to max and I have absolutely no idea what should I do! I think I will find out in a month or so!! :)

    Regards,
    Mohamad
  • 0 in reply to Mohamad K
    TI__Mastermind 29650 points
    Hi Mohamad,

    If the amplitude is that low something is probably driving the pins from the outside of the chip (level shifter) or you are measuring with a low impedance probe (e.g. 50 ohm). The IO's are driving between GND and VDD(battery), if the battery voltage is less than 1V the SensorTag would not even start.

    Regards,
    Svend
  • 0 in reply to svendbt
    Intellectual 750 points
    Hi svendbt
    I've checked again. When I use sensortag alone (with battery), the uart txamplitude is OK (between VDD and GND) but when I plug the DevPack Debug board (with usb power) the uart tx amplitude is between VDD and VDD-0.5V!! I am really wonder why! I have checked on 3 boards and all treat this way.
    Regards,
    Mohamad
  • 0 in reply to Mohamad K
    Intellectual 750 points
    Well, I finally found the solution.
    Beside changing the assigned pin to Uart in code, you should remove the battery from sensortag! By doing this, the DevPack board wont go in debugging mode and it wont load the Uart pins.
  • 0 in reply to Mohamad K
    Guru 21435 points
    Hi Mohamad,

    I am getting the exact same issue you were experiencing, and have outlined the details here - e2e.ti.com/.../441616

    I have tried your battery solution, but it makes no difference if it is in or out.

    Have you found out anything else regarding this issue that I could use to assist me resolve the problem.

    Regards,
    Glenn.
  • 0 in reply to Glenn Vassallo
    Intellectual 750 points

    Hi Glenn
    In my experience, if I connect my debugPack to PC it is a XDS110 Debugger. If I connect debugPack to sensorTag with battery then attach usb cable again it is a XDS110 debugger. but if I attach the debugger to sensorTag without battery THEN attach usb cable to debugger it appears as some tiva... device. In this case you cant use it for programming or debugging but the uart IOs are working.
    Hope it was helpful.

    Regards,
    Mohamad

  • 0
    Prodigy 70 points

    Hi!

    Had the same problem on an RF06 board - There is a jumper named "enable UART over XDS100v3". If I pull that jumper, everything worked fine. If not, the chip didn't receive any data.

    Cheers!

  • 0 in reply to Lukas Mayer
    TI__Guru 71526 points
    Thanks for the verification and update, Lukas! Much appreciated.
    ~Leonard