uart.c
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/*
* Copyright (C) 2014-2015 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_sam3
* @ingroup drivers_periph_uart
* @{
*
* @file
* @brief Low-level UART driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include "cpu.h"
#include "board.h"
#include "periph/uart.h"
#include "periph/gpio.h"
#define ENABLE_DEBUG (0)
#include "debug.h"
/**
* @brief Allocate memory to store the callback functions.
*/
static uart_isr_ctx_t ctx[UART_NUMOF];
int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
{
Uart *dev;
/* make sure given device is valid */
if (uart >= UART_NUMOF) {
return UART_NODEV;
}
/* get base register */
dev = uart_config[uart].dev;
/* register callback */
ctx[uart].rx_cb = rx_cb;
ctx[uart].arg = arg;
/* enable clock */
uart_poweron(uart);
/* reset configuration */
dev->UART_CR = 0;
dev->UART_IDR = 0x0000ffff;
/* configure pins */
gpio_init_mux(uart_config[uart].tx_pin, uart_config[uart].mux);
if (rx_cb) {
gpio_init_mux(uart_config[uart].rx_pin, uart_config[uart].mux);
}
/* configure baud rate and set mode to 8N1 */
dev->UART_BRGR = (CLOCK_CORECLOCK / (16 * baudrate));
dev->UART_MR = UART_MR_PAR_NO | US_MR_CHRL_8_BIT;
if (rx_cb) {
dev->UART_CR = UART_CR_RXEN | UART_CR_TXEN | UART_CR_RSTSTA;
NVIC_EnableIRQ(uart_config[uart].irqn);
dev->UART_IER = UART_IER_RXRDY;
}
else {
dev->UART_CR = UART_CR_TXEN | UART_CR_RSTSTA;
}
return UART_OK;
}
void uart_write(uart_t uart, const uint8_t *data, size_t len)
{
Uart *dev = uart_config[uart].dev;
for (size_t i = 0; i < len; i++) {
while (!(dev->UART_SR & UART_SR_TXRDY)) {}
dev->UART_THR = data[i];
}
}
void uart_poweron(uart_t uart)
{
PMC->PMC_PCER0 |= (1 << uart_config[uart].pmc_id);
}
void uart_poweroff(uart_t uart)
{
PMC->PMC_PCER0 &= ~(1 << uart_config[uart].pmc_id);
}
static inline void isr_handler(int num)
{
Uart *dev = uart_config[num].dev;
if (dev->UART_SR & UART_SR_RXRDY) {
ctx[num].rx_cb(ctx[num].arg, (uint8_t)dev->UART_RHR);
}
cortexm_isr_end();
}
#ifdef UART_0_ISR
void UART_0_ISR(void)
{
isr_handler(0);
}
#endif
#ifdef UART_1_ISR
void UART_1_ISR(void)
{
isr_handler(1);
}
#endif
#ifdef UART_2_ISR
void UART_2_ISR(void)
{
isr_handler(2);
}
#endif
#ifdef UART_3_ISR
void UART_3_ISR(void)
{
isr_handler(3);
}
#endif