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Added IRQ USART example for the f4 discovery board.

This commit is contained in:
Piotr Esden-Tempski 2013-01-28 18:26:46 -08:00
parent 20bfcaeb1c
commit 8b062bb659
3 changed files with 154 additions and 0 deletions
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examples/stm32/f4/stm32f4-discovery/usart_irq/Makefile Normal file
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##
## This file is part of the libopencm3 project.
##
## Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
##
## This library is free software: you can redistribute it and/or modify
## it under the terms of the GNU Lesser General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## This library is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU Lesser General Public License for more details.
##
## You should have received a copy of the GNU Lesser General Public License
## along with this library. If not, see <http://www.gnu.org/licenses/>.
##
BINARY = usart_irq
LDSCRIPT = ../stm32f4-discovery.ld
include ../../Makefile.include

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examples/stm32/f4/stm32f4-discovery/usart_irq/README Normal file
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------------------------------------------------------------------------------
README
------------------------------------------------------------------------------
This example program echoes data sent in on USART2 on the
ST STM32F4DISCOVERY eval board. Uses interrupts for that purpose.
Connect your TTL RX device line to PA2 on the discovery board.
Connect your TTL TX device line to PA3 on the discovery board.
The terminal settings for the receiving device/PC are 38400 8n1.
The sending is done in a blocking way in the code.

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examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c Normal file
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/*
* This file is part of the libopencm3 project.
*
* Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
* Copyright (C) 2011 Stephen Caudle <scaudle@doceme.com>
* Copyright (C) 2013 Piotr Esden-Tempski <piotr@esden.net>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libopencm3/stm32/f4/rcc.h>
#include <libopencm3/stm32/f4/gpio.h>
#include <libopencm3/stm32/usart.h>
#include <libopencm3/cm3/nvic.h>
void clock_setup(void)
{
/* Enable GPIOD clock for LED & USARTs. */
rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPDEN);
rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPAEN);
/* Enable clocks for USART2. */
rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);
}
void usart_setup(void)
{
/* Enable the USART2 interrupt. */
nvic_enable_irq(NVIC_USART2_IRQ);
/* Setup GPIO pins for USART2 transmit. */
gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
/* Setup GPIO pins for USART2 receive. */
gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO3);
gpio_set_output_options(GPIOA, GPIO_OTYPE_OD, GPIO_OSPEED_25MHZ, GPIO3);
/* Setup USART2 TX and RX pin as alternate function. */
gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
gpio_set_af(GPIOA, GPIO_AF7, GPIO3);
/* Setup USART2 parameters. */
usart_set_baudrate(USART2, 38400);
usart_set_databits(USART2, 8);
usart_set_stopbits(USART2, USART_STOPBITS_1);
usart_set_mode(USART2, USART_MODE_TX_RX);
usart_set_parity(USART2, USART_PARITY_NONE);
usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);
/* Enable USART2 Receive interrupt. */
usart_enable_rx_interrupt(USART2);
/* Finally enable the USART. */
usart_enable(USART2);
}
void gpio_setup(void)
{
/* Setup GPIO pin GPIO12 on GPIO port D for LED. */
gpio_mode_setup(GPIOD, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO12);
}
int main(void)
{
clock_setup();
gpio_setup();
usart_setup();
while (1) {
__asm__("NOP");
}
return 0;
}
void usart2_isr(void)
{
static u8 data = 'A';
/* Check if we were called because of RXNE. */
if (((USART_CR1(USART2) & USART_CR1_RXNEIE) != 0) &&
((USART_SR(USART2) & USART_SR_RXNE) != 0)) {
/* Indicate that we got data. */
gpio_toggle(GPIOD, GPIO12);
/* Retrieve the data from the peripheral. */
data = usart_recv(USART2);
/* Enable transmit interrupt so it sends back the data. */
usart_enable_tx_interrupt(USART2);
}
/* Check if we were called because of TXE. */
if (((USART_CR1(USART2) & USART_CR1_TXEIE) != 0) &&
((USART_SR(USART2) & USART_SR_TXE) != 0)) {
/* Put data into the transmit register. */
usart_send(USART2, data);
/* Disable the TXE interrupt as we don't need it anymore. */
usart_disable_tx_interrupt(USART2);
}
}