RTOS/CC2650: UART_read losing characters not reading full string.

Hi Alexis,

I really don't think the null values would be the problem because I'm simulating the same data stream through a serial monitor with several null characters. 

Moreover I cannot change the data stream I am getting in the UART as it comes from a Coldfire MCU whose firmware I do not have access to.

And as can be seen in the output the null characters between the words are read. Is there any way to increase the size of the input buffer beyond 32 bytes?

But I am certain that the data being sent is correct as I verified by directly reading it on a UART to USB cable. 

So my problem lies in reading the data,:

I'm receiving 100 characters every 500ms. But the input buffer size is only 32 bytes, so the first 32 characters are read correctly , but when the next UART read is invoked it again reads another 32 characters but not from where it left off last time. So I'm losing characters inbetween reads.

The solution to this seems to be to increase to the input buffer size beyond 32 or decrease the time taken between consecutive reads.

I am not sure how to do both, any help would be appreciated.

Thank you.

Hi Aravindh,

Have you looked at the "Receive Continuously in UART_MODE_CALLBACK" use case? It can be found here:

<SDK_INSTALL_DIR>/docs/tidrivers/doxygen/html/_u_a_r_t_c_c26_x_x_8h.html

Thanks,

Alexis

Hey Alexis, 

I tired all of the implementations n the link that you mentioned.

But unfortunately none of them work. Would using a ring buffer implementation in UART_read be of any use. I don't completely understand the difference in using the FIFO implementation and the ring buffer implementation.

Thank you for the help, and quick response,

Aravindh.

Hi,

Also when the Rx buffer is receiving data, what happens when the data exceeds 32 bytes does it fall off and is it lost or, does it overwrite the buffer from the beginning? Is there a way to switch between these modes?

Thanks.

Hi Aravindh,

Can you include a code snippet of how you are configuring your UART?

Thanks,

Alexis

Hey, 

this is inside my main() function.


int main(){
  /* Register Application callback to trap asserts raised in the Stack */
  RegisterAssertCback(AssertHandler);

  PIN_init(BoardGpioInitTable);

#ifndef POWER_SAVING
  /* Set constraints for Standby, powerdown and idle mode */
  Power_setConstraint(PowerCC26XX_SB_DISALLOW);
  Power_setConstraint(PowerCC26XX_IDLE_PD_DISALLOW);
#endif // POWER_SAVING

  /* Initialize the RTOS Log formatting and output to UART in Idle thread.
   * Note: Define xdc_runtime_Log_DISABLE_ALL to remove all impact of Log.
   * Note: NULL as Params gives 115200,8,N,1 and Blocking mode */

  UART_init();
  char i[5] = "hello";
  System_printf("%s\n",i);
//  System_flush();
  Types_FreqHz freq;
  BIOS_getCpuFreq(&freq);
  System_printf("hi: %d, lo: %d", freq.hi, freq.lo);
  System_flush();



  uint32_t timeout = 20000;
  UART_Params params;
  //
         // Init UART and specify non-default parameters
   UART_Params_init(&params);
   params.baudRate      = 460800;
//   params.writeDataMode = UART_DATA_BINARY;
//   params.readTimeout = 5000*(1000/Clock_tickPeriod);
   params.readMode      = UART_MODE_CALLBACK;
   params.readDataMode  = UART_DATA_BINARY;
//   params.readReturnMode = UART_RETURN_FULL;
   params.readEcho       = UART_ECHO_OFF;
   //   params.writeMode     = UART_MODE_BLOCKING;
//   params.writeCallback = UART_writeCB;
   params.readCallback  = readCallback;

//   params.stopBits = UART_STOP_ONE;
//   params.parityType = UART_PAR_NONE;
//   params.dataLength = UART_LEN_8;
//   params.readTimeout   = timeout;


  handle = UART_open(Board_UART, &params);
..
..
..
}

Thanks,
Aravindh