111 lines
4.7 KiB
C
111 lines
4.7 KiB
C
/* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU 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 program 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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/** @brief library to get time from a DCF77 module
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* @file rtc_dcf77.c
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @date 2016
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* @note peripherals used: GPIO @ref rtc_dcf77_gpio, timer @ref rtc_dcf77_timer
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*/
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/* standard libraries */
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#include <stdint.h> // standard integer types
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#include <stdlib.h> // general utilities
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#include <stdio.h>
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/* STM32 (including CM3) libraries */
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#include <libopencm3/stm32/rcc.h> // real-time control clock library
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#include <libopencm3/stm32/gpio.h> // general purpose input output library
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#include <libopencm3/stm32/spi.h> // SPI library
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#include <libopencm3/stm32/timer.h> // timer library
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#include <libopencm3/cm3/nvic.h> // interrupt handler
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include "rtc_dcf77.h" // RTC DCF77 library API
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#include "global.h" // common methods
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volatile bool rtc_dcf77_time_flag = false;
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void rtc_dcf77_setup(void)
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{
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// setup enable output
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rcc_periph_clock_enable(RTC_DCF77_ENABLE_RCC); // enable clock GPIO peripherial
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gpio_set_mode(RTC_DCF77_ENABLE_PORT, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, RTC_DCF77_ENABLE_PIN); // set pin to output push-pull to be able to enable the module
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rtc_dcf77_off(); // disable module at start
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// setup signal input
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rcc_periph_clock_enable(RTC_DCF77_SIGNAL_RCC); // enable clock for signal input peripheral
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gpio_set_mode(RTC_DCF77_SIGNAL_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, RTC_DCF77_SIGNAL_PIN); // set signal pin to input
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rcc_periph_clock_enable(RCC_AFIO); // enable alternate function clock for external interrupt
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exti_select_source(RTC_DCF77_SIGNAL_EXTI, RTC_DCF77_SIGNAL_PORT); // mask external interrupt of this pin only for this port
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exti_set_trigger(RTC_DCF77_SIGNAL_EXTI, EXTI_TRIGGER_BOTH); // trigger on both edges
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exti_enable_request(RTC_DCF77_SIGNAL_EXTI); // enable external interrupt
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nvic_enable_irq(RTC_DCF77_SIGNAL_IRQ); // enable interrupt
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// setup timer to measure pulses
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rcc_periph_clock_enable(RTC_DCF77_TIMER_RCC); // enable clock for timer peripheral
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timer_reset(RTC_DCF77_TIMER); // reset timer state
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timer_set_mode(RTC_DCF77_TIMER, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock, edge alignment (simple count), and count up
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timer_set_prescaler(RTC_DCF77_TIMER, RTC_DCF77_TIMER_MAX_TIME*(rcc_ahb_frequency/1000)/(1<<16)); // set prescaler to count up to the maximum time
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timer_enable_counter(RTC_DCF77_TIMER); // start timer to measure time
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}
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void rtc_dcf77_on(void)
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{
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gpio_clear(RTC_DCF77_ENABLE_PORT, RTC_DCF77_ENABLE_PIN); // enable module by pull pin low
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}
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void rtc_dcf77_off(void)
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{
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gpio_set(RTC_DCF77_ENABLE_PORT, RTC_DCF77_ENABLE_PIN); // disable module by pull pin high
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}
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/** @brief interrupt service routine called when signal edge is detected */
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void RTC_DCF77_SIGNAL_ISR(void)
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{
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exti_reset_request(RTC_DCF77_SIGNAL_EXTI); // reset interrupt
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static uint16_t old_state = 0; // save last port state to detect difference
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static uint8_t pulse = 0; // next pulse number in the DCF77 frame
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//static uint16_t pulse_rising = 0, pulse_falling = 0; // time on when the last pulse edge has been detected
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static uint16_t pulse_rising = 0;
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uint16_t time = timer_get_counter(RTC_DCF77_TIMER); // get timer value
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uint16_t new_state = gpio_get(RTC_DCF77_SIGNAL_PORT, RTC_DCF77_SIGNAL_PIN); // save last port state to detect difference
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if (old_state!=new_state) { // pulse edge detected
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if (new_state) { // rising edge
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time = (uint32_t)(time-pulse_rising)*RTC_DCF77_TIMER_MAX_TIME/(1<<16); // get time since last rising edge (integer underflow possible)
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if (time < 900) { // ignore glitches
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goto end;
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} else if (time < 1100) { // a normal pulse
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pulse = (pulse+1)%59; // go to next pulse (there should be no more than 59)
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} else if (time < 1900) { // ignore glitch
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goto end;
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} else if (time < 2100) { // first pulse of a frame
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pulse = 0;
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} else { // something is wrong, restart
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pulse = 0;
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}
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led_toggle();
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pulse_rising = 0; // save new edge
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timer_set_counter(RTC_DCF77_TIMER, 0); // reset timer to count
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printf("%u\n", pulse);
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}
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}
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end:
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old_state = new_state; // save new state
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}
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