stm32f1/main.c

/* This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdio.h> // standard I/O facilities
#include <stdlib.h> // standard utilities
#include <unistd.h> // standard streams
#include <errno.h> // error number utilities

/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/cm3/scb.h> // vector table definition
#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
#include <libopencm3/cm3/nvic.h> // interrupt utilities
#include <libopencm3/stm32/exti.h> // external interrupt utilities

/* own libraries */
#include "global.h" // board definitions
#include "usart.h" // USART utilities
#include "usb_cdcacm.h" // USB CDC ACM utilities

/* flag set in interrupts to be processed in main taks */
volatile bool button_flag = false; // button has been presse

/* default output (i.e. for printf) */
int _write(int file, char *ptr, int len)
{
	int i;

	if (file == STDOUT_FILENO || file == STDERR_FILENO) {
		for (i = 0; i < len; i++) {
			if (ptr[i] == '\n') { // add carrier return before line feed. this is recommended for most UART terminals
				usart_putchar_nonblocking('\r'); // a second line feed doesn't break the display
				cdcacm_putchar('\r'); // a second line feed doesn't break the display
			}
			usart_putchar_nonblocking(ptr[i]); // send byte over USART
			cdcacm_putchar(ptr[i]); // send byte over USB
		}
		return i;
	}
	errno = EIO;
	return -1;
}

/* switch on LED */
void led_on(void)
{
#ifdef SYSTEM_BOARD
	gpio_clear(LED_PORT, LED_PIN);
#elif MAPLE_MINI
	gpio_set(LED_PORT, LED_PIN);
#endif
}

/* switch off LED */
void led_off(void)
{
#ifdef SYSTEM_BOARD
	gpio_set(LED_PORT, LED_PIN);
#elif MAPLE_MINI
	gpio_clear(LED_PORT, LED_PIN);
#endif
}

/* toggle LED */
void led_toggle(void)
{
	gpio_toggle(LED_PORT, LED_PIN);
}

int main(void)
{	
	SCB_VTOR = (uint32_t) 0x08002000; // relocate vector table because of the bootloader

	rcc_clock_setup_in_hse_8mhz_out_72mhz(); // use 8 MHz high speed external clock to generate 72 MHz internal clock
    usart_setup(); // setup USART (for printing)
    cdcacm_setup(); // setup USB CDC ACM (for printing)
    setbuf(stdout, NULL); // set standard out buffer to NULL to immediately print   
    setbuf(stderr, NULL); // set standard error buffer to NULL to immediately print

	// setup LED
	rcc_periph_clock_enable(LED_RCC); // enable clock for LED
	gpio_set_mode(LED_PORT, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, LED_PIN); // set LED pin to 'output push-pull'
	led_off(); // switch off LED to indicate setup started

	// setup button
#if defined(BUTTON_RCC) && defined(BUTTON_PORT) && defined(BUTTON_PIN) && defined(BUTTON_EXTI) && defined(BUTTON_IRQ)
	rcc_periph_clock_enable(BUTTON_RCC); // enable clock for button
	gpio_set_mode(BUTTON_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, BUTTON_PIN); // set button pin to input
	rcc_periph_clock_enable(RCC_AFIO); // enable alternate function clock for external interrupt
	exti_select_source(BUTTON_EXTI, BUTTON_PORT); // mask external interrupt of this pin only for this port
	exti_set_trigger(BUTTON_EXTI, EXTI_TRIGGER_BOTH); // trigger on both edge
	exti_enable_request(BUTTON_EXTI); // enable external interrupt
	nvic_enable_irq(BUTTON_IRQ); // enable interrupt
#endif

	printf("welcome to the STM32F1 CuVoodoo example code\n"); // print welcome message
	led_on(); // switch on LED to indicate setup completed

	bool action = false; // if an action has been performed don't go to sleep
	button_flag = false; // reset button flag
	/* toggle the LED with every transmitted character */
	while (true) { // infinite loop
		while (usart_received) { // echo every received character
			action = true; // action has been performed
			led_toggle(); // toggle LED
			printf("%c",usart_getchar()); // transmit receive character
		}
		while (cdcacm_received) { // echo every received character
			action = true; // action has been performed
			led_toggle(); // toggle LED
			printf("%c",cdcacm_getchar()); // transmit receive character
		}
		while (button_flag) {
			button_flag = false; // reset flag
			action = true; // action has been performed
			led_toggle(); // toggle LED
		}
		// go to sleep if nothing had to be done, else recheck for activity
		if (action) {
			action = false;
		} else {
			__WFI(); // go to sleep
		}
	}

	return 0;
}

#if defined(BUTTON_ISR) && defined(BUTTON_EXTI)
void BUTTON_ISR(void)
{
	exti_reset_request(BUTTON_EXTI); // reset interrupt
	button_flag = true; // perform button action
}
#endif