boards/evkmimx8mq/driver_examples/uart/interrupt/uart_interrupt.c

/*
 * Copyright (c) 2015, Freescale Semiconductor, Inc.
 * Copyright 2016-2017 NXP
 * All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include "board.h"
#include "fsl_uart.h"

#include "pin_mux.h"
#include "clock_config.h"
/*******************************************************************************
 * Definitions
 ******************************************************************************/
#define DEMO_UART            UART2
#define DEMO_UART_CLK_FREQ   BOARD_DEBUG_UART_CLK_FREQ
#define DEMO_UART_BAUDRATE   115200U
#define DEMO_IRQn            UART2_IRQn
#define DEMO_UART_IRQHandler UART2_IRQHandler

/*! @brief Ring buffer size (Unit: Byte). */
#define DEMO_RING_BUFFER_SIZE 16

/*! @brief Ring buffer to save received data. */

/*******************************************************************************
 * Prototypes
 ******************************************************************************/

/*******************************************************************************
 * Variables
 ******************************************************************************/

uint8_t g_tipString[] =
    "Uart functional API interrupt example\r\nBoard receives characters then sends them out\r\nNow please input:\r\n";

/*
  Ring buffer for data input and output, in this example, input data are saved
  to ring buffer in IRQ handler. The main function polls the ring buffer status,
  if there are new data, then send them out.
  Ring buffer full: (((rxIndex + 1) % DEMO_RING_BUFFER_SIZE) == txIndex)
  Ring buffer empty: (rxIndex == txIndex)
*/
uint8_t demoRingBuffer[DEMO_RING_BUFFER_SIZE];
volatile uint16_t txIndex; /* Index of the data to send out. */
volatile uint16_t rxIndex; /* Index of the memory to save new arrived data. */

/*******************************************************************************
 * Code
 ******************************************************************************/

void DEMO_UART_IRQHandler(void)
{
    uint8_t data;

    /* If new data arrived. */
    if ((UART_GetStatusFlag(DEMO_UART, kUART_RxDataReadyFlag)) || (UART_GetStatusFlag(DEMO_UART, kUART_RxOverrunFlag)))
    {
        data = UART_ReadByte(DEMO_UART);

        /* If ring buffer is not full, add data to ring buffer. */
        if (((rxIndex + 1) % DEMO_RING_BUFFER_SIZE) != txIndex)
        {
            demoRingBuffer[rxIndex] = data;
            rxIndex++;
            rxIndex %= DEMO_RING_BUFFER_SIZE;
        }
    }
    SDK_ISR_EXIT_BARRIER;
}

/*!
 * @brief Main function
 */
int main(void)
{
    status_t status;
    uart_config_t config;

    /* Board specific RDC settings */
    BOARD_RdcInit();
    BOARD_InitPins();
    BOARD_BootClockRUN();
    BOARD_InitMemory();

    /*
     * config.baudRate_Bps = 115200U;
     * config.parityMode = kUART_ParityDisabled;
     * config.dataBitsCount = kUART_EightDataBits;
     * config.stopBitCount = kUART_OneStopBit;
     * config.txFifoWatermark = 2;
     * config.rxFifoWatermark = 1;
     * config.enableTx = false;
     * config.enableRx = false;
     */
    UART_GetDefaultConfig(&config);
    config.baudRate_Bps = DEMO_UART_BAUDRATE;
    config.enableTx     = true;
    config.enableRx     = true;

    status = UART_Init(DEMO_UART, &config, DEMO_UART_CLK_FREQ);
    if (kStatus_Success != status)
    {
        return kStatus_Fail;
    }

    /* Send g_tipString out. */
    UART_WriteBlocking(DEMO_UART, g_tipString, sizeof(g_tipString) / sizeof(g_tipString[0]) - 1);

    /* Enable RX interrupt. */
    UART_EnableInterrupts(DEMO_UART, kUART_RxDataReadyEnable | kUART_RxOverrunEnable);
    EnableIRQ(DEMO_IRQn);

    while (1)
    {
        /* Send data only when UART TX register is empty and ring buffer has data to send out. */
        while ((UART_GetStatusFlag(DEMO_UART, kUART_TxReadyFlag)) && (rxIndex != txIndex))
        {
            UART_WriteByte(DEMO_UART, demoRingBuffer[txIndex]);
            txIndex++;
            txIndex %= DEMO_RING_BUFFER_SIZE;
        }
    }
}