sensor: fix sampling rate with OCXO
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jaseg
parent
6ab3ac3dff
commit
7f0041bf10
3 changed files with 49 additions and 41 deletions
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@ -32,12 +32,11 @@ static uint16_t current_seq = 0;
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static int current_buf = 0;
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static void adc_dma_init(void);
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static void adc_timer_init(int psc, int ivl);
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static void adc_dma_launch(void);
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/* Mode that can be used for debugging */
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void adc_configure_scope_mode(int sampling_interval_ns) {
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void adc_init() {
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adc_dma_init();
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/* Clock from PCLK/4 instead of the internal exclusive high-speed RC oscillator. */
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@ -56,14 +55,6 @@ void adc_configure_scope_mode(int sampling_interval_ns) {
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/* Enable conversion */
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ADC1->CR |= ADC_CR_ADEN;
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ADC1->CR |= ADC_CR_ADSTART;
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/* An ADC conversion takes 1.1667us, so to be sure we don't get data overruns we limit sampling to every 1.5us.
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Since we don't have a spare PLL to generate the ADC sample clock and re-configuring the system clock just for this
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would be overkill we round to 250ns increments. The minimum sampling rate is about 60Hz due to timer resolution. */
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int cycles = sampling_interval_ns > 1500 ? sampling_interval_ns/250 : 6;
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if (cycles > 0xffff)
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cycles = 0xffff;
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adc_timer_init(12/*250ns/tick*/, cycles);
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}
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static void adc_dma_init() {
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@ -91,8 +82,8 @@ void adc_dma_launch() {
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DMA1_Channel1->CCR |= DMA_CCR_EN; /* Enable channel */
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}
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static void adc_timer_init(int psc, int ivl) {
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TIM1->BDTR = TIM_BDTR_MOE; /* MOE is needed even though we only "output" a chip-internal signal TODO: Verify this. */
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void adc_timer_init(int psc, int ivl) {
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TIM1->BDTR = TIM_BDTR_MOE; /* MOE is needed even though we only "output" a chip-internal signal */
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TIM1->CCMR2 = (6<<TIM_CCMR2_OC4M_Pos); /* PWM Mode 1 to get a clean trigger signal */
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TIM1->CCER = TIM_CCER_CC4E; /* Enable capture/compare unit 4 connected to ADC */
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TIM1->CCR4 = 1; /* Trigger at start of timer cycle */
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@ -20,7 +20,7 @@
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#include "global.h"
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void adc_init(void);
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void adc_configure_scope_mode(int sampling_interval_ns);
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void adc_init();
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void adc_timer_init(int psc, int ivl);
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#endif/*__ADC_H__*/
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@ -25,6 +25,7 @@ volatile union leds leds;
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volatile int32_t gps_1pps_period_sysclk = -1;
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int main(void) {
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/* Get GPIOA and SPI1 up to flash status LEDs */
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RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
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RCC->APB2ENR |= RCC_APB2ENR_SPI1EN;
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@ -60,9 +61,11 @@ int main(void) {
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SPI1->CR1 |= SPI_CR1_SPE;
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*((volatile uint8_t*)&(SPI1->DR)) = 0xff;
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/* Wait for OCXO to settle */
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for (int i=0; i<1000000; i++)
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;
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/* Switch clock to PLL based on OCXO input */
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RCC->CR |= RCC_CR_HSEBYP;
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RCC->CR |= RCC_CR_HSEON;
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RCC->CFGR &= ~RCC_CFGR_PLLMUL_Msk & ~RCC_CFGR_SW_Msk & ~RCC_CFGR_PPRE_Msk & ~RCC_CFGR_HPRE_Msk;
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@ -73,11 +76,13 @@ int main(void) {
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while (!(RCC->CR&RCC_CR_PLLRDY));
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RCC->CFGR |= (2<<RCC_CFGR_SW_Pos);
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SystemCoreClockUpdate();
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/* Start systick */
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SysTick_Config(SystemCoreClock/10); /* 100ms interval */
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NVIC_EnableIRQ(SysTick_IRQn);
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NVIC_SetPriority(SysTick_IRQn, 3<<5);
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/* Turn on lots of neat things */
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/* Turn on rest of periphery */
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RCC->AHBENR |= RCC_AHBENR_DMAEN | RCC_AHBENR_GPIOBEN | RCC_AHBENR_FLITFEN | RCC_AHBENR_CRCEN;
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RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN | RCC_APB2ENR_ADCEN | RCC_APB2ENR_DBGMCUEN |\
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RCC_APB2ENR_TIM1EN | RCC_APB2ENR_TIM16EN | RCC_APB2ENR_USART1EN;
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@ -88,17 +93,17 @@ int main(void) {
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GPIOB->AFR[0] = (0<<GPIO_AFRL_AFRL1_Pos);
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GPIOB->PUPDR = 2<<GPIO_PUPDR_PUPDR1_Pos;
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/* Configure TIM16 for LED update via SPI */
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TIM16->CR2 = 0;
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TIM16->DIER = TIM_DIER_UIE | TIM_DIER_CC1IE;
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TIM16->CCMR1 = 0;
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TIM16->CCR1 = 32;
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TIM16->PSC = 48-1; /* 1us */
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TIM16->ARR = 1000-1; /* 1ms */
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TIM16->CR1 = TIM_CR1_CEN;
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NVIC_EnableIRQ(TIM16_IRQn);
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/* Configure TIM14 for GPS 1pps input capture */
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TIM14->CCMR1 = (1<<TIM_CCMR1_CC1S_Pos) | (3<<TIM_CCMR1_IC1F_Pos);
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TIM14->CCER = TIM_CCER_CC1E;
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TIM14->PSC = 1;
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@ -106,10 +111,10 @@ int main(void) {
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TIM14->DIER = TIM_DIER_CC1IE | TIM_DIER_UIE;
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TIM14->EGR = TIM_EGR_UG;
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TIM14->CR1 |= TIM_CR1_CEN;
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NVIC_EnableIRQ(TIM14_IRQn);
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adc_configure_scope_mode(1000000);
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adc_init(1000000);
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adc_timer_init(243, 200); /* 19.44 MHz / 243 -> 200 kHz; /200 -> 1 kHz */
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usart_dma_init();
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@ -129,29 +134,9 @@ void TIM14_IRQHandler(void) {
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if (sr & TIM_SR_CC1OF) {
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TIM14->SR &= ~(TIM_SR_CC1IF | TIM_SR_CC1OF);
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tim14_sr_cc1of();
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} else if (sr & TIM_SR_CC1IF) { /* CC1 event (GPS 1pps input) */
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/* Don't reset update event: If update event arrives while CC1 event is being processed leave UIF set to process
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* update event immediately after return from ISR. */
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uint16_t ccr = TIM14->CCR1;
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if (in_sync) {
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uint32_t new_period = gps_1pps_period + ccr;
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if (new_period < 20000000 || new_period > 30000000) { /* Signal out of range */
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in_sync = false;
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gps_1pps_period_sysclk = -1;
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gps_1pps_period = (uint32_t)-1;
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} else {
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gps_1pps_period_sysclk = new_period;
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gps_1pps_period = 0;
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update_inc = 0x10000 - ccr; /* remaining cycles in this period */
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leds.pps = 200; /* ms */
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}
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} else {
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gps_1pps_period = 0;
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update_inc = 0x10000 - ccr; /* remaining cycles in this period */
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in_sync = true;
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}
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} else { /* update */
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}
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if (sr & TIM_SR_UIF) {
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TIM14->SR &= ~TIM_SR_UIF;
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if (in_sync) {
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gps_1pps_period += update_inc;
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@ -163,6 +148,38 @@ void TIM14_IRQHandler(void) {
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}
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update_inc = 0x10000;
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}
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if (sr & TIM_SR_CC1IF) { /* CC1 event (GPS 1pps input) */
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/* Don't reset update event: If update event arrives while CC1 event is being processed leave UIF set to process
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* update event immediately after return from ISR. */
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uint16_t ccr = TIM14->CCR1;
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if (in_sync) {
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uint32_t new_period = gps_1pps_period + ccr;
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if (new_period < 20000000 || new_period > 30000000) { /* Signal out of range */
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in_sync = false;
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gps_1pps_period_sysclk = -1;
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gps_1pps_period = (uint32_t)-1;
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} else {
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if ((sr & TIM_SR_UIF) /* we processed an update event in this ISR */
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&& (ccr > 0xc000) /* and the capture happened late in the cycle */
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) {
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gps_1pps_period_sysclk = new_period - 0x10000;
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update_inc = 0x10000;
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gps_1pps_period = 0x10000 - ccr;
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} else {
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gps_1pps_period_sysclk = new_period;
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update_inc = 0x10000 - ccr; /* remaining cycles in this period */
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gps_1pps_period = 0;
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}
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leds.pps = 200; /* ms */
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}
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} else {
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gps_1pps_period = 0;
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update_inc = 0x10000 - ccr; /* remaining cycles in this period */
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in_sync = true;
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}
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}
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}
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void TIM16_IRQHandler(void) {
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