mirror of
https://github.com/eddyem/stm32samples.git
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83 lines
2.5 KiB
C
83 lines
2.5 KiB
C
/*
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* This file is part of the libopencm3 project.
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*
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* Copyright (C) 2013 Chuck McManis <cmcmanis@mcmanis.com>
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* Copyright (C) 2013 Onno Kortmann <onno@gmx.net>
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* Copyright (C) 2013 Frantisek Burian <BuFran@seznam.cz> (merge)
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <libopencm3/stm32/rcc.h>
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#include <libopencm3/stm32/gpio.h>
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#include <libopencm3/cm3/nvic.h>
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#include <libopencm3/cm3/systick.h>
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#include "stm32f0.h"
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/* Called when systick fires */
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void sys_tick_handler(void){
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pin_toggle(GPIOB, GPIO3);
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}
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/*
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* Set up timer to fire every x milliseconds
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* This is a unusual usage of systick, be very careful with the 24bit range
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* of the systick counter! You can range from 1 to 2796ms with this.
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*/
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static void systick_setup(int xms){
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static int curms = 0;
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if(curms == xms) return;
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// 6MHz
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systick_set_clocksource(STK_CSR_CLKSOURCE_EXT);
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/* clear counter so it starts right away */
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STK_CVR = 0;
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systick_set_reload(6000 * xms);
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systick_counter_enable();
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systick_interrupt_enable();
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curms = xms;
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}
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/* set STM32 to clock by 48MHz from HSI oscillator */
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static void clock_setup(void){
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rcc_clock_setup_in_hsi_out_48mhz();
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//rcc_clock_setup_in_hse_8mhz_out_48mhz();
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/* Enable clocks to the GPIO subsystems (A&B) */
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RCC_AHBENR = RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN;
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}
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static void gpio_setup(void){
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/* Set green led (PB3) as output */
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gpio_mode_setup(GPIOB, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO3);
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/* D2 - PA12 - switch blink rate (pullup input) */
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gpio_mode_setup(GPIOA, GPIO_MODE_INPUT, GPIO_PUPD_PULLUP, GPIO12);
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}
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int main(void){
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clock_setup();
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gpio_setup();
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/* 500ms ticks => 1000ms period => 1Hz blinks */
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systick_setup(500);
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/* Do nothing in main loop */
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while (1){
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if(pin_read(GPIOA, GPIO12)) systick_setup(125); // no jumper - 4Hz
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else systick_setup(500); // 1Hz
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}
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}
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