CC1312R: Generating UART callback per 1byte receiving on CC1312R

/*
 * Copyright (c) 2015-2019, Texas Instruments Incorporated
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 *    from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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/*
 *  ======== uartecho.c ========
 */
#include <stdint.h>
#include <stddef.h>

/* Driver Header files */
#include <ti/drivers/GPIO.h>
#include <ti/drivers/UART.h>

/* Driver configuration */
#include "ti_drivers_config.h"

uint32_t wantedRxBytes = 1;            // Number of bytes received so far
//uint8_t rxBuf[512];   // Receive buffer
uint8_t rxBuf[1];   // Receive buffer
uint8_t txBuf[1];
uint8_t count = 0;


// Read callback function
void readCallback(UART_Handle handle, void *rxBuf, size_t size)
{
   size_t i;
   // Make sure we received all expected bytes
   if (size == wantedRxBytes)
   {
       GPIO_write(CONFIG_GPIO_LED_0, CONFIG_GPIO_LED_ON);
       txBuf[0] = ((uint8_t*)rxBuf)[0];

      // Echo the bytes received back to transmitter
//      UART_write(handle, txBuf, size);

      // Start another read, with size the same as it was during first call to
      GPIO_write(CONFIG_GPIO_LED_0, CONFIG_GPIO_LED_OFF);
   }
   else {
       // Handle error or call to UART_readCancel()
   }
   UART_read(handle, rxBuf, wantedRxBytes);
}


/*
 *  ======== mainThread ========
 */
void *mainThread(void *arg0)
{
    char        input;
    const char  echoPrompt[] = "Echoing characters:\r\n";
    UART_Handle uart;
    UART_Params uartParams;

    int i;

    rxBuf[0] = 0;
	txBuf[0] = 0;

    /* Call driver init functions */
    GPIO_init();
    UART_init();

    /* Configure the LED pin */
    GPIO_setConfig(CONFIG_GPIO_LED_0, GPIO_CFG_OUT_STD | GPIO_CFG_OUT_LOW);

    /* Turn on user LED */
//    GPIO_write(CONFIG_GPIO_LED_0, CONFIG_GPIO_LED_ON);

    /* Create a UART with data processing off. */
    UART_Params_init(&uartParams);
    uartParams.readMode = UART_MODE_CALLBACK;
    uartParams.readCallback = readCallback;
    uartParams.writeDataMode = UART_DATA_BINARY;
    uartParams.readDataMode = UART_DATA_BINARY;
    uartParams.readReturnMode = UART_RETURN_FULL;
    uartParams.readEcho = UART_ECHO_OFF;
    uartParams.baudRate = 9600;

    uart = UART_open(CONFIG_UART_0, &uartParams);

    if (uart == NULL) {
        /* UART_open() failed */
        while (1);
    }

    UART_write(uart, echoPrompt, sizeof(echoPrompt));

    UART_read(uart, rxBuf, 1);

    /* Loop forever echoing */
    while (1)
    {
        // UART_read(uart, &input, 1);
        // UART_write(uart, &input, 1);
    }
}