/* This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . * */ /** library to detect Nikon infrared remote control trigger using 38 kHz infrared demodulator * @file * @author King Kévin * @date 2018 * @note peripherals used: timer channel @ref ir_nikon_timer */ /* standard libraries */ #include // standard integer types #include // standard boolean type /* STM32 (including CM3) libraries */ #include // Cortex M3 utilities #include // interrupt handler #include // real-time control clock library #include // general purpose input output library #include // timer utilities /* own libraries */ #include "ir_nikon.h" // own definitions #include "global.h" // common methods /** @defgroup ir_nikon_timer timer peripheral used to measure signal timing for signal decoding * @{ */ #define IR_NIKON_TIMER 4 /**< timer peripheral */ #define IR_NIKON_CHANNEL 3 /**< channel used as input capture */ #define IR_NIKON_JITTER 20 /**< signal timing jitter in % tolerated in timing */ #define IR_NIKON_EXTERNAL_PULLUP true /**< if an external pull-up resistor is already present on the infrared demodulator OUT signal */ /** @} */ volatile bool ir_nikon_trigger_flag = false; /** the mark and space durations (in us) corresponding to the Nikon IR sequence (static, measured from a remote clone) */ const uint16_t ir_nikon_sequence[] = {2000, 28000, 400, 1580, 400, 3580, 400, 63200, 2000, 28000, 400, 1580, 400, 3580, 400}; // actually there is a 2 pulse trailer, but we skip it to have a faster trigger: 70000, 540, 7200, 580 void ir_nikon_setup(void) { // setup timer to measure signal timing for bit decoding (use timer channel as input capture) rcc_periph_clock_enable(RCC_TIM_CH(IR_NIKON_TIMER, IR_NIKON_CHANNEL)); // enable clock for GPIO peripheral rcc_periph_clock_enable(RCC_TIM(IR_NIKON_TIMER)); // enable clock for timer peripheral rcc_periph_clock_enable(RCC_AFIO); // enable clock for alternative functions #if IR_NIKON_EXTERNAL_PULLUP gpio_set_mode(TIM_CH_PORT(IR_NIKON_TIMER, IR_NIKON_CHANNEL), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, TIM_CH_PIN(IR_NIKON_TIMER, IR_NIKON_CHANNEL)); // setup GPIO pin as input #else gpio_set(TIM_CH_PORT(IR_NIKON_TIMER, IR_NIKON_CHANNEL), TIM_CH_PIN(IR_NIKON_TIMER, IR_NIKON_CHANNEL)); // idle is high (using pull-up resistor) gpio_set_mode(TIM_CH_PORT(IR_NIKON_TIMER, IR_NIKON_CHANNEL), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, TIM_CH_PIN(IR_NIKON_TIMER, IR_NIKON_CHANNEL)); // setup GPIO pin as input #endif timer_reset(TIM(IR_NIKON_TIMER)); // reset timer state timer_set_mode(TIM(IR_NIKON_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 // codes are repeated every 110 ms, thus we need to measure at least this duration to detect repeats correctly // the 16-bit timer is by far precise enough to measure the smallest 560 us burst timer_set_prescaler(TIM(IR_NIKON_TIMER), (70 * (rcc_ahb_frequency / 1000) / (1 << 16)) - 1); // set the prescaler so this 16 bits timer overflow after 70 ms (to ignore the second sequence) timer_ic_set_input(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL), TIM_IC_IN_TI(IR_NIKON_CHANNEL)); // configure ICx to use TIn timer_ic_set_filter(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL), TIM_IC_CK_INT_N_8); // use small filter (noise reduction is more important than timing) timer_ic_set_polarity(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL), TIM_IC_FALLING); // capture on falling edge (IR bursts are active low on IR demodulators) timer_ic_set_prescaler(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL), TIM_IC_PSC_OFF); // don't use any prescaler since we want to capture every pulse timer_clear_flag(TIM(IR_NIKON_TIMER), TIM_SR_UIF); // clear flag timer_update_on_overflow(TIM(IR_NIKON_TIMER)); // only use counter overflow as UEV source (use overflow as start time or timeout) timer_enable_irq(TIM(IR_NIKON_TIMER), TIM_DIER_UIE); // enable update interrupt for timer timer_clear_flag(TIM(IR_NIKON_TIMER), TIM_SR_CCIF(IR_NIKON_CHANNEL)); // clear input compare flag timer_ic_enable(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL)); // enable capture interrupt only when IR burst timer_enable_irq(TIM(IR_NIKON_TIMER), TIM_DIER_CCIE(IR_NIKON_CHANNEL)); // enable capture interrupt nvic_enable_irq(NVIC_TIM_IRQ(IR_NIKON_TIMER)); // catch interrupt in service routine timer_enable_counter(TIM(IR_NIKON_TIMER)); // enable timer } /** interrupt service routine called for timer * @note this could be improve by ignoring short noise burst, but works good enough */ void TIM_ISR(IR_NIKON_TIMER)(void) { static uint8_t burst_count = 0; // the mark or space count static uint32_t burst_start = 0; // time of current mark/space start static uint32_t bits = 0; // the received code bits static struct ir_nec_code_t code; // the last code received (don't trust the user exposed ir_nec_code_received) static bool valid = false; // if the last IR activity is a valid code if (timer_get_flag(TIM(IR_NIKON_TIMER), TIM_SR_UIF)) { // overflow update event happened timer_clear_flag(TIM(IR_NIKON_TIMER), TIM_SR_UIF); // clear flag goto reset; } else if (timer_get_flag(TIM(IR_NIKON_TIMER), TIM_SR_CCIF(IR_NIKON_CHANNEL))) { // edge detected on input capture uint32_t time = TIM_CCR(IR_NIKON_TIMER, IR_NIKON_CHANNEL); // save captured bit timing (this also clears the flag) time = (time * (TIM_PSC(TIM(IR_NIKON_TIMER)) + 1)) / (rcc_ahb_frequency / 1000000); // calculate time in us if (time < burst_start) { // this should not happen goto error; } time -= burst_start; // calculate mark/space burst time if (0 == burst_count) { // start of very first IR mark for the AGC burst timer_set_counter(TIM(IR_NIKON_TIMER), 0); // reset timer counter burst_start = 0; // reset code timer time = 0; // ignore first burst } else if (1 == burst_count) { // end of AGC mark if (time > 9000 * (100 - IR_NIKON_JITTER) / 100 && time < 9000 * (100 + IR_NIKON_JITTER) / 100) { // AGC mark } else { goto error; } } else if (2 == burst_count) { // end of AGC space if (time > 4500 * (100 - IR_NIKON_JITTER) / 100 && time < 4500 * (100 + IR_NIKON_JITTER) / 100) { // AGC code space bits = 0; // reset previously received bits valid = false; // invalidate previously received code (since this is not a repeat) } else if (time > 2250 * (100 - IR_NIKON_JITTER) / 100 && time < 2250 * (100 + IR_NIKON_JITTER) / 100) { // AGC repeat space if (valid) { code.repeat = true; ir_nec_code_received.repeat = code.repeat; ir_nec_code_received.address = code.address; ir_nec_code_received.command = code.command; ir_nec_code_received_flag = true; goto reset; // wait for next code } else { goto error; } } else { goto reset; // not the correct header } } else if (burst_count <= (1 + 32) * 2) { // the code bits if (burst_count % 2) { // bit mark end if (time > 560 * (100 - IR_NIKON_JITTER) / 100 && time < 560 * (100 + IR_NIKON_JITTER) / 100) { // bit mark } else { goto error; } } else { // bit space end bits <<= 1; if (time > (2250 - 560) * (100 - IR_NIKON_JITTER) / 100 && time < (2250 - 560) * (100 + IR_NIKON_JITTER) / 100) { // bit 1space bits |= 1; // save bit } else if (time > (1125 - 560) * (100 - IR_NIKON_JITTER) / 100 && time < (1125 - 560) * (100 + IR_NIKON_JITTER) / 100) { // bit 0 space bits |= 0; // save bit } else { goto error; } } if ((1 + 32) * 2 == burst_count) { // the code is complete uint8_t address = (bits >> 24) & 0xff; // get 8 address bits uint8_t naddress = (bits >> 16) & 0xff; // get negated 8 address bits uint8_t command = (bits >> 8) & 0xff; // get 8 command bits uint8_t ncommand = (bits >> 0) & 0xff; // get negate 8 commend bits if (0xff != (address ^ naddress)) { // the address and its negative do not match goto error; } if (0xff != (command ^ ncommand)) { // the command and its negative do not match goto error; } valid = true; // remember we have a valid signal code.repeat = false; // this is not a repeat code code.address = address; // save decoded address code.command = command; // save decoded command ir_nec_code_received.repeat = code.repeat; // transfer code to user ir_nec_code_received.address = code.address; // transfer code to user ir_nec_code_received.command = code.command; // transfer code to user ir_nec_code_received_flag = true; ir_nec_code_received_flag = true; // notify user about the new code goto reset; // wait for next code } } else { // this should not happen goto error; } if (burst_count % 2) { timer_ic_set_polarity(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL), TIM_IC_FALLING); // wait for end of space } else { timer_ic_set_polarity(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL), TIM_IC_RISING); // wait for end of mark } burst_count++; // wait for next burst burst_start += time; // save current burst start } else { // no other interrupt should occur while (true); // unhandled exception: wait for the watchdog to bite } return; error: valid = false; // invalidate previously received code reset: timer_ic_set_polarity(TIM(IR_NIKON_TIMER), TIM_IC(IR_NIKON_CHANNEL), TIM_IC_FALLING); // wait for next IR mark burst ignore = false; // don't ignore pulses anymore burst_count = 0; // reset state burst_start = 0; // reset state }