86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/*
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* This file is part of the libopencm3 project.
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*
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* Copyright (C) 2010 Thomas Otto <tommi@viadmin.org>
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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/f1/rcc.h>
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#include <libopencm3/stm32/f1/flash.h>
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#include <libopencm3/stm32/f1/gpio.h>
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#include <libopencm3/stm32/timer.h>
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#include <libopencm3/cm3/nvic.h>
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void gpio_setup(void)
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{
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/* Enable GPIOB clock. */
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rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPBEN);
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/* Set GPIO6/7 (in GPIO port B) to 'output push-pull' for the LEDs. */
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gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ,
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GPIO_CNF_OUTPUT_PUSHPULL, GPIO6);
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gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ,
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GPIO_CNF_OUTPUT_PUSHPULL, GPIO7);
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}
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void nvic_setup(void)
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{
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/* Without this the timer interrupt routine will never be called. */
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nvic_enable_irq(NVIC_TIM2_IRQ);
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nvic_set_priority(NVIC_TIM2_IRQ, 1);
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}
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void tim2_isr(void)
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{
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gpio_toggle(GPIOB, GPIO6); /* LED2 on/off. */
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TIM_SR(TIM2) &= ~TIM_SR_UIF; /* Clear interrrupt flag. */
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}
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int main(void)
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{
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rcc_clock_setup_in_hse_16mhz_out_72mhz();
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gpio_setup();
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nvic_setup();
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gpio_clear(GPIOB, GPIO7); /* LED1 on */
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gpio_set(GPIOB, GPIO6); /* LED2 off */
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rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_TIM2EN);
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/*
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* The goal is to let the LED2 glow for a second and then be
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* off for a second.
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*/
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/* Set timer start value. */
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TIM_CNT(TIM2) = 1;
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/* Set timer prescaler. 72MHz/1440 => 50000 counts per second. */
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TIM_PSC(TIM2) = 1440;
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/* End timer value. If this is reached an interrupt is generated. */
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TIM_ARR(TIM2) = 50000;
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/* Update interrupt enable. */
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TIM_DIER(TIM2) |= TIM_DIER_UIE;
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/* Start timer. */
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TIM_CR1(TIM2) |= TIM_CR1_CEN;
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while (1); /* Halt. */
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return 0;
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}
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