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CC26XX - UART Help and Clarification Appreciated

Shaba Abhiram
Intellectual 540 points
Other Parts Discussed in Thread: CC2650

Hey Folks,

I have a couple of questions related to the UART usage in a cc2650 EM + SmartRF06 EB setup. I am fairly new to Ti development, so please bear with my potentially silly questions. 

Setup so far:

1. I have a working SmartRF06 EB w/ a 7ID cc2650 EM module

2. I can confirm that the board works fine for I2C and other such protocols

3. I am trying to hook up an external module to this device using UART0

4. I removed the "Enable UART over XDSv3" jumper and jumped the JTAG pins to the UART pins in the XDSV3 Bypass as stated in the Ti RTOS guide

5. The current version of the RTOS does not support RTS CTS, so I have a 3 wire setup (EM TX --> Device Rx, EM RX <-- Device Tx, EM GND <--> Device GND)

6. I have modified the UART_Echo example to send and receive some data to this device

Issues:

1. When I do a blocked UART_write(...) - The write semaphore never gets cleared (but I know that the Device is getting the command being sent since my serial connection to a PC with a screen session sees the data being relayed)

2. When I do a blocked UART_read(...) - I see reads come through succesfully when the other device boots up (as it emits these messages on start), however, I do not see any response on the Ti side

I will be updating my RTOS version to enable CTS and RTS to see if this brings any relief. 

Thank you for any help and feedback!

  • 0
    Intellectual 540 points
    Upgraded the RTOS, but my problems were other things:

    1. On the SmartRF EB - you need to jump the shared JTAG / UART pins to send the UART to the EM Tx / Rx
    2. You also need to remove the "Enable UART Backchannel" jumper

    However, I still seem to run into a few issues:
    1. I seem to have to do a read (even if its just a single byte, which typically returns 0) using UART_read(...)
    2. Once I do this, the writes work as expected, but subsequent reads seem to only contain a maximum of 32 bytes no matter how large I make the read buffer, am I missing anything here?
    3. Still have not tried getting flow control to work, but I figure that will be straightforward once this is comprehended
  • 0 in reply to Shaba Abhiram
    TI__Guru**** 202106 points
    Shaba,

    Since this post is unrelated to MSP430 devices I am moving it to the ZigBee®, 6LoWPAN & 802.15.4 MAC Forum so that it may be properly addressed.

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    Intellectual 540 points

    Thank you Ryan! Apologies - I am new around these parts :) Appreciate the help!