libopencm3/examples/stm32/f1/obldc/usart/usart.c

91 lines
2.7 KiB
C

/*
* 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/>.
*/
#include <libopencm3/stm32/f1/rcc.h>
#include <libopencm3/stm32/f1/gpio.h>
#include <libopencm3/stm32/usart.h>
void clock_setup(void)
{
rcc_clock_setup_in_hse_8mhz_out_72mhz();
/* Enable GPIOA clock (for LED GPIOs). */
rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN);
/* Enable clocks for GPIO port B (for GPIO_USART1_TX) and USART1. */
rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPBEN);
rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_AFIOEN);
rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_USART1EN);
}
void usart_setup(void)
{
/* Setup GPIO6 (in GPIO port A) to 'output push-pull' for LED use. */
gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
GPIO_CNF_OUTPUT_PUSHPULL, GPIO6);
AFIO_MAPR |= AFIO_MAPR_USART1_REMAP;
/* Setup GPIO pin GPIO_USART3_TX/GPIO10 on GPIO port B for transmit. */
gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ,
GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_RE_TX);
/* Setup UART parameters. */
usart_set_baudrate(USART1, 230400);
usart_set_databits(USART1, 8);
usart_set_stopbits(USART1, USART_STOPBITS_1);
usart_set_mode(USART1, USART_MODE_TX);
usart_set_parity(USART1, USART_PARITY_NONE);
usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);
/* Finally enable the USART. */
usart_enable(USART1);
}
void gpio_setup(void)
{
/* Set GPIO6 (in GPIO port A) to 'output push-pull'. */
gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
GPIO_CNF_OUTPUT_PUSHPULL, GPIO6);
}
int main(void)
{
int i, j = 0, c = 0;
clock_setup();
gpio_setup();
usart_setup();
/* Blink the LED (PA6) on the board with every transmitted byte. */
while (1) {
gpio_toggle(GPIOA, GPIO6); /* LED on/off */
usart_send_blocking(USART1, c + '0'); /* Send a byte. */
c = (c == 9) ? 0 : c + 1; /* Increment c. */
if ((j++ % 80) == 0) { /* Newline after line full. */
usart_send_blocking(USART1, '\r');
usart_send_blocking(USART1, '\n');
}
for (i = 0; i < 800000; i++) /* Wait a bit. */
__asm__("nop");
}
return 0;
}