CC2652R: UART read taking too long

Dekel Gilboa

Part Number: CC2652R

I'm using CC2652R development kit to communicate a modem via UART interface.

This is the UART configuration i'm using:

UART_Params uart_params;
UART_Params_init(&uart_params);
uart_params.writeDataMode  = UART_DATA_BINARY;
uart_params.writeMode      = UART_MODE_BLOCKING;
uart_params.readDataMode   = UART_DATA_BINARY;
uart_params.readReturnMode = UART_RETURN_NEWLINE;
uart_params.readEcho       = UART_ECHO_OFF;
uart_params.readMode       = UART_MODE_BLOCKING;
uart_params.readTimeout    = msecs2Tick(ME310G1_READ_TIMEOUT); //5 seconds waiting for modem answer
uart_params.baudRate       = ME310G1_READ_BAUDRATE;

Since reading in mode 'UART_RETURN_NEWLINE' doesn't work, i'm waiting 5 seconds for every write and read operations - waiting for read timeout to end.

This mechanism works fine for me, except it's taking too much time.

I tried to implement different read method using read mode 'UART_MODE_CALLBACK' (and a callback) in order to speed up read process like this:

read(void * destination, size_t size)
{
    size_t receive = 0;
    uint8_t * dst = (uint8_t *)destination;
    int result = 0;
    while(size > 0 && result != UART_STATUS_ERROR)
    {
          //Read single byte
          char dummy;
          result = UART_read(g_uart_handle, &dummy, 1);
          if(result != UART_STATUS_ERROR)
          {
              dst[receive] = dummy;
              receive++;
              size--;
          }
    }
}

The problem with this implementation is that i'm reading zeros bytes since the modem doesn't answer back fast enough.

If i'm inserting a small delay after every byte read, i manage to read appropriately part of the responds from the modem.

Is there something i can do in order to solve this issue ?

I can supply further information if needed.

Thx,

Dekel

over 4 years ago

0 Ryan Brown1 over 4 years ago

TI__Guru**** 217957 points

Hi Dekel,

Please refer to UART.h from the TI Drivers Runtime API. If the modem cannot provide a newline and you would like to process incoming bytes immediately then I recommend you set readDataMode = UART_DATA_BINARY and readReturnMode = UART_RETURN_FULL to process bytes individually in your application.

Regards,
Ryan

0 Dekel Gilboa over 4 years ago in reply to Ryan Brown1

Prodigy 115 points

Thanks for replaying !

The modem can provide a new line but i read at the forums that the option 'UART_RETURN_NEWLINE' isn't support by the driver, and it didn't work for me when i tried to use it.

Basically i came up with a solution but I'm not sure if it's going to work all the time.

It looks like:

size_t me310g1_read(void * destination, size_t size)
{
    size_t receive = 0;

    if (g_uart_handle)
    {
        //We are trying to read few times since the modem might not answer fast enough
        int retries = 10;
        while(receive < 10 && retries > 0)
        {
            receive = UART_read(g_uart_handle, destination, size);
            retries--;
        }
    }

     return receive;
}

I split the reads to ten attempts and each one of them is half a second. Besides that, I changed my UART configurations to:

uart_params.writeDataMode  = UART_DATA_BINARY;
uart_params.writeMode      = UART_MODE_BLOCKING;
uart_params.readDataMode   = UART_DATA_BINARY;
uart_params.readReturnMode = UART_RETURN_FULL;
uart_params.readEcho       = UART_ECHO_OFF;
uart_params.readMode       = UART_MODE_BLOCKING;
uart_params.readTimeout    = msecs2Tick(500);
uart_params.baudRate       = ME310G1_READ_BAUDRATE;

If you come up with a different solution i would be happy to read it

Thanks,

Dekel

0 Ryan Brown1 over 4 years ago in reply to Dekel Gilboa

TI__Guru**** 217957 points

UART_RETURN_NEWLINE is supported and is the default value for UART_Params_init. There could be a misinterpretation of the driver or settings that is causing it not to operate as expected. I would still encourage you to consider callbacks, there is a uart2callback example which you can reference and port to the UART driver. Here is a relevant E2E post (and another one) as well.

Regards,
Ryan

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CC2652R: UART read taking too long