RIOT/cpu/sam3x8e/periph/uart.c

/*
 * Copyright (C) 2014 Freie Universität Berlin
 *
 * This file is subject to the terms and conditions of the GNU Lesser General
 * Public License. See the file LICENSE in the top level directory for more
 * details.
 */

/**
 * @ingroup     driver_periph
 * @{
 *
 * @file        uart.c
 * @brief       Low-level UART driver implementation
 *
 * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
 *
 * @}
 */

#include "board.h"
#include "cpu.h"

#include "periph/uart.h"
#include "periph_conf.h"


/**
 * @brief Each UART device has to store two callbacks.
 */
typedef struct {
    void (*rx_cb)(char);
    void (*tx_cb)(void);
} uart_conf_t;

/**
 * @brief Allocate memory to store the callback functions.
 */
static uart_conf_t config[UART_NUMOF];





int uart_init(uart_t uart, uint32_t baudrate, void (*rx_cb)(char), void (*tx_cb)(void))
{
    /* initialize basic functionality */
    int res = uart_init_blocking(uart, baudrate);
    if (res != 0) {
        return res;
    }

    /* register callbacks */
    config[uart].rx_cb = rx_cb;
    config[uart].tx_cb = tx_cb;

    /* configure interrupts and enable RX interrupt */
    switch (uart) {
        case UART_0:
            UART_0_DEV->UART_IER = UART_IER_RXRDY;
        break;
        case UART_UNDEFINED:
            return -2;
    }
    return 0;
}

int uart_init_blocking(uart_t uart, uint32_t baudrate)
{
    uint16_t clock_divider = F_CPU / (16 * baudrate);
    switch (uart) {
#if UART_0_EN
        case UART_0:
            /* configure PINS */
            UART_0_PORT->PIO_PDR = UART_0_PINS;
            UART_0_PORT->PIO_ABSR &= ~UART_0_PINS;

            /* set clock divider */
            UART_0_DEV->UART_BRGR = clock_divider;
            /* set to normal mode without parity */
            UART_0_DEV->UART_MR = UART_MR_PAR_NO | UART_MR_CHMODE_NORMAL;
            /* enable receiver and transmitter and reset status bits */
            UART_0_DEV->UART_CR = UART_CR_RXEN | UART_CR_TXEN | UART_CR_RSTSTA;
            break;
#endif
        case UART_UNDEFINED:
            return -2;
            break;
    }
    return 0;
}

void uart_tx_begin(uart_t uart)
{

}

void uart_tx_end(uart_t uart)
{

}

int uart_write(uart_t uart, char data)
{
    switch (uart) {
        case UART_0:
            UART_0_DEV->UART_THR = data;
            break;
        case UART_UNDEFINED:
            return -1;
    }
    return 1;
}

int uart_read_blocking(uart_t uart, char *data)
{
    switch (uart) {
        case UART_0:
            while (!(UART_0_DEV->UART_SR & UART_SR_RXRDY));
            *data = (char)UART_0_DEV->UART_RHR;
            break;
        case UART_UNDEFINED:
            return -1;
    }
    return 1;
}

int uart_write_blocking(uart_t uart, char data)
{
    switch (uart) {
        case UART_0:
            while (!(UART_0_DEV->UART_SR & UART_SR_TXRDY));
            UART_0_DEV->UART_THR = data;
            break;
        case UART_UNDEFINED:
            return -1;
    }
    return 1;
}