3673e4059b
as a way of creating accurately timed delays. A simple 'msleep' is implemented by watching the system clock to wait a certain number of milleseconds before it returns. Its a bit more accurate than a for loop, although it really shines when your running multiple threads.
92 lines
2.5 KiB
C
92 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) 2009 Uwe Hermann <uwe@hermann-uwe.de>
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* Copyright (C) 2011 Damjan Marion <damjan.marion@gmail.com>
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* Copyright (C) 2011 Mark Panajotovic <marko@electrontube.org>
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* Copyright (C) 2013 Chuck McManis <cmcmanis@mcmanis.com>
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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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/* This version derived from fancy blink */
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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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void msleep(uint32_t);
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/* monotonically increasing number of milliseconds from reset
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* overflows every 49 days if you're wondering
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*/
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volatile uint32_t system_millis;
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/* Called when systick fires */
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void sys_tick_handler(void) {
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system_millis++;
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}
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/* sleep for delay milliseconds */
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void msleep(uint32_t delay) {
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uint32_t wake = system_millis + delay;
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while (wake > system_millis) ;
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}
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/* Set up a timer to create 1mS ticks. */
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static void systick_setup(void)
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{
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/* clock rate / 1000 to get 1mS interrupt rate */
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systick_set_reload(168000);
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systick_set_clocksource(STK_CTRL_CLKSOURCE_AHB);
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systick_counter_enable();
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/* this done last */
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systick_interrupt_enable();
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}
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/* Set STM32 to 168 MHz. */
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static void clock_setup(void)
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{
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rcc_clock_setup_hse_3v3(&hse_8mhz_3v3[CLOCK_3V3_168MHZ]);
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/* Enable GPIOD clock. */
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rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPDEN);
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}
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static void gpio_setup(void)
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{
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/* Set GPIO11-15 (in GPIO port D) to 'output push-pull'. */
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gpio_mode_setup(GPIOD, GPIO_MODE_OUTPUT,
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GPIO_PUPD_NONE, GPIO11 | GPIO12 | GPIO13 | GPIO14 | GPIO15);
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}
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int main(void)
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{
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clock_setup();
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gpio_setup();
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systick_setup();
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/* Set two LEDs for wigwag effect when toggling. */
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gpio_set(GPIOD, GPIO12 | GPIO14);
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/* Blink the LEDs (PD12, PD13, PD14 and PD15) on the board. */
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while (1) {
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gpio_toggle(GPIOD, GPIO12 | GPIO13 | GPIO14 | GPIO15);
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msleep(100);
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}
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return 0;
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}
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