165 lines
3.9 KiB
C
165 lines
3.9 KiB
C
/*
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* This file is part of the libopencm3 project.
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*
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* Copyright (C) 2011 Piotr Esden-Tempski <piotr@esden.net>
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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/cm3/nvic.h>
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#include <libopencm3/stm32/rcc.h>
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#include <libopencm3/stm32/gpio.h>
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#include <libopencm3/stm32/timer.h>
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#ifndef ARRAY_LEN
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#define ARRAY_LEN(array) (sizeof((array))/sizeof((array)[0]))
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#endif
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#define LED1_PORT GPIOC
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#define LED1_PIN GPIO12
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/* Morse standard timings */
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#define ELEMENT_TIME 500
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#define DIT (1*ELEMENT_TIME)
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#define DAH (3*ELEMENT_TIME)
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#define INTRA (1*ELEMENT_TIME)
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#define INTER (3*ELEMENT_TIME)
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#define WORD (7*ELEMENT_TIME)
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uint16_t frequency_sequence[] = {
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DIT,
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INTRA,
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DIT,
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INTRA,
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DIT,
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INTER,
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DAH,
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INTRA,
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DAH,
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INTRA,
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DAH,
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INTER,
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DIT,
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INTRA,
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DIT,
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INTRA,
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DIT,
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WORD,
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};
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int frequency_sel = 0;
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static void clock_setup(void)
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{
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rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]);
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}
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static void gpio_setup(void)
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{
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/* Enable GPIO clock for leds. */
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rcc_periph_clock_enable(RCC_GPIOC);
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/* Enable led as output */
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gpio_set_mode(LED1_PORT, GPIO_MODE_OUTPUT_50_MHZ,
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GPIO_CNF_OUTPUT_PUSHPULL, LED1_PIN);
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gpio_set(LED1_PORT, LED1_PIN);
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}
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static void tim_setup(void)
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{
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/* Enable TIM2 clock. */
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rcc_periph_clock_enable(RCC_TIM2);
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/* Enable TIM2 interrupt. */
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nvic_enable_irq(NVIC_TIM2_IRQ);
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/* Reset TIM2 peripheral to defaults. */
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rcc_periph_reset_pulse(RST_TIM2);
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/* Timer global mode:
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* - No divider
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* - Alignment edge
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* - Direction up
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* (These are actually default values after reset above, so this call
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* is strictly unnecessary, but demos the api for alternative settings)
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*/
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timer_set_mode(TIM2, TIM_CR1_CKD_CK_INT,
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TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
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/*
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* Please take note that the clock source for STM32 timers
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* might not be the raw APB1/APB2 clocks. In various conditions they
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* are doubled. See the Reference Manual for full details!
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* In our case, TIM2 on APB1 is running at double frequency, so this
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* sets the prescaler to have the timer run at 5kHz
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*/
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timer_set_prescaler(TIM2, ((rcc_apb1_frequency * 2) / 5000));
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/* Disable preload. */
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timer_disable_preload(TIM2);
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timer_continuous_mode(TIM2);
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/* count full range, as we'll update compare value continuously */
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timer_set_period(TIM2, 65535);
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/* Set the initual output compare value for OC1. */
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timer_set_oc_value(TIM2, TIM_OC1, frequency_sequence[frequency_sel++]);
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/* Counter enable. */
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timer_enable_counter(TIM2);
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/* Enable Channel 1 compare interrupt to recalculate compare values */
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timer_enable_irq(TIM2, TIM_DIER_CC1IE);
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}
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void tim2_isr(void)
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{
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if (timer_get_flag(TIM2, TIM_SR_CC1IF)) {
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/* Clear compare interrupt flag. */
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timer_clear_flag(TIM2, TIM_SR_CC1IF);
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/*
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* Get current timer value to calculate next
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* compare register value.
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*/
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uint16_t compare_time = timer_get_counter(TIM2);
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/* Calculate and set the next compare value. */
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uint16_t frequency = frequency_sequence[frequency_sel++];
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uint16_t new_time = compare_time + frequency;
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timer_set_oc_value(TIM2, TIM_OC1, new_time);
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if (frequency_sel == ARRAY_LEN(frequency_sequence)) {
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frequency_sel = 0;
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}
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/* Toggle LED to indicate compare event. */
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gpio_toggle(LED1_PORT, LED1_PIN);
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}
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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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tim_setup();
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while (1) {
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;
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}
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return 0;
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}
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