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LAUNCHXL-CC2640R2: UART RX Pullup?

Tianqi Liu
Prodigy 70 points

Part Number: LAUNCHXL-CC2640R2
Other Parts Discussed in Thread: BLE-STACK

We are trying to  do UART communication from BLE module to other Processor.

We see that Data sent from BLE module is received by other chip over UART but whereas when that chip sends the data BLE module is not able to receive it.

When we probed that the rx line on BLE side we see that When data bit is 0 it is not going to complete 0 level, whereas when we disconnect and probe on UART tx of other chip we see level is properly going to 0 level.

Is there any Pull up or pull down required on BLE module to receive data properly over UART ?

  • 0
    TI__Mastermind 33460 points
    Hello,

    No pullup/pulldowns are required by the device to do UART communications but sounds like your UART pins may not have been initialized correctly?
    Are you using the default module and have you added the UART pins to the PIN init array?

    Are you able to confirm that the UART driver is open and setup to receive data on the pins you are sending data?

    I would begin to debug this by running the uart_echo example from TI-RTOS to see if you are able to receive data and validate the hardware setup. You may need to modify your board file if you are not using default pins.
  • 0 in reply to Sean2
    Prodigy 70 points
    Hi, Sean,
    Thanks for your prompt response!

    I am using the default RXD pin and I did not modify any board files. After test with uart_echo example I'm observing same pattern, however, it goes to complete 0 if send from serial connection (debug uart?).
  • 0 in reply to Tianqi Liu
    TI__Mastermind 33460 points

    Hello,

    I believe this is a hardware setup issue then. What is the module you are using and do you know what package size (7x7, 5x5, etc) that it uses?

    I think that your UART may not be setup correctly for the module you are using (may require board file modifications), and thus you are getting a NULL handle and either crashing or sitting idle.

    This section of the Software Developer's Guide explains how to run the BLE stack on custom (non TI) hardware. You might find it helpful:

    http://software-dl.ti.com/lprf/sdg-latest/html/ble-stack/index.html#running-the-sdk-on-custom-boards

  • 0 in reply to Sean2
    Prodigy 20 points
    Helloc
    I met the same problem when I use LAUNCHXL_CC2640R2.
    I add npi_tl_uart.c to my project and initialize in function simpleBLEPeriphreal_init().
    It can send data from UART to PC,but can not receive data from PC UART.
    How can I solve this problem?