uart.c
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/*
* Copyright (C) 2014 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_stm32f0
* @{
*
* @file
* @brief Low-level UART driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include "cpu.h"
#include "periph/uart.h"
/**
* @brief Allocate memory to store the callback functions.
*/
static uart_isr_ctx_t uart_config[UART_NUMOF];
static USART_TypeDef *const uart_port[UART_NUMOF] = {
#if UART_0_EN
[UART_0] = UART_0_DEV,
#endif
#if UART_1_EN
[UART_1] = UART_1_DEV,
#endif
};
int init_base(uart_t uart, uint32_t baudrate);
int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
{
int res;
/* initialize UART in blocking mode first */
res = init_base(uart, baudrate);
if (res != UART_OK) {
return res;
}
/* enable global interrupt and configure the interrupts priority */
switch (uart) {
#if UART_0_EN
case UART_0:
NVIC_EnableIRQ(UART_0_IRQ);
UART_0_DEV->CR1 |= USART_CR1_RXNEIE;
break;
#endif
#if UART_1_EN
case UART_1:
NVIC_EnableIRQ(UART_1_IRQ);
UART_1_DEV->CR1 |= USART_CR1_RXNEIE;
break;
#endif
}
/* register callbacks */
uart_config[uart].rx_cb = rx_cb;
uart_config[uart].arg = arg;
return UART_OK;
}
int init_base(uart_t uart, uint32_t baudrate)
{
USART_TypeDef *dev = 0;
GPIO_TypeDef *port = 0;
uint32_t rx_pin = 0;
uint32_t tx_pin = 0;
uint8_t af = 0;
uint32_t mid;
uint16_t mantissa;
uint8_t fraction;
/* enable UART and port clocks and select devices */
switch (uart) {
#if UART_0_EN
case UART_0:
dev = UART_0_DEV;
port = UART_0_PORT;
rx_pin = UART_0_RX_PIN;
tx_pin = UART_0_TX_PIN;
af = UART_0_AF;
/* enable clocks */
UART_0_CLKEN();
UART_0_PORT_CLKEN();
break;
#endif
#if UART_1_EN
case UART_1:
dev = UART_1_DEV;
port = UART_1_PORT;
tx_pin = UART_1_TX_PIN;
rx_pin = UART_1_RX_PIN;
af = UART_1_AF;
/* enable clocks */
UART_1_CLKEN();
UART_1_PORT_CLKEN();
break;
#endif
default:
return UART_NODEV;
}
/* Make sure port and dev are != NULL here, i.e. that the variables are
* assigned in all non-returning branches of the switch at the top of this
* function. */
assert(port != NULL);
assert(dev != NULL);
/* configure RX and TX pins, set pin to use alternative function mode */
port->MODER &= ~(3 << (rx_pin * 2) | 3 << (tx_pin * 2));
port->MODER |= 2 << (rx_pin * 2) | 2 << (tx_pin * 2);
/* and assign alternative function */
if (rx_pin < 8) {
port->AFR[0] &= ~(0xf << (rx_pin * 4));
port->AFR[0] |= af << (rx_pin * 4);
}
else {
port->AFR[1] &= ~(0xf << ((rx_pin - 8) * 4));
port->AFR[1] |= af << ((rx_pin - 8) * 4);
}
if (tx_pin < 8) {
port->AFR[0] &= ~(0xf << (tx_pin * 4));
port->AFR[0] |= af << (tx_pin * 4);
}
else {
port->AFR[1] &= ~(0xf << ((tx_pin - 8) * 4));
port->AFR[1] |= af << ((tx_pin - 8) * 4);
}
/* configure UART to mode 8N1 with given baudrate */
mid = (CLOCK_CORECLOCK / baudrate);
mantissa = (uint16_t)(mid / 16);
fraction = (uint8_t)(mid - (mantissa * 16));
dev->BRR = ((mantissa & 0x0fff) << 4) | (0x0f & fraction);
/* enable receive and transmit mode */
dev->CR1 |= USART_CR1_UE | USART_CR1_TE | USART_CR1_RE;
return UART_OK;
}
void uart_write(uart_t uart, const uint8_t *data, size_t len)
{
USART_TypeDef *dev = uart_port[uart];
for (size_t i = 0; i < len; i++) {
while (!(dev->ISR & USART_ISR_TXE)) {}
dev->TDR = data[i];
}
}
void uart_poweron(uart_t uart)
{
switch (uart) {
#if UART_0_EN
case UART_0:
UART_0_CLKEN();
break;
#endif
#if UART_1_EN
case UART_1:
UART_1_CLKEN();
break;
#endif
}
}
void uart_poweroff(uart_t uart)
{
switch (uart) {
#if UART_0_EN
case UART_0:
UART_0_CLKDIS();
break;
#endif
#if UART_1_EN
case UART_1:
UART_1_CLKDIS();
break;
#endif
}
}
static inline void irq_handler(uint8_t uartnum, USART_TypeDef *dev)
{
if (dev->ISR & USART_ISR_RXNE) {
uint8_t data = (uint8_t)dev->RDR;
uart_config[uartnum].rx_cb(uart_config[uartnum].arg, data);
}
else if (dev->ISR & USART_ISR_ORE) {
/* do nothing on overrun */
dev->ICR |= USART_ICR_ORECF;
}
cortexm_isr_end();
}
#if UART_0_EN
void UART_0_ISR(void)
{
irq_handler(UART_0, UART_0_DEV);
}
#endif
#if UART_1_EN
void UART_1_ISR(void)
{
irq_handler(UART_1, UART_1_DEV);
}
#endif