diff options
Diffstat (limited to 'fw/adc.c')
| -rw-r--r-- | fw/adc.c | 149 |
1 files changed, 132 insertions, 17 deletions
@@ -17,7 +17,8 @@ #include "adc.h" -volatile struct adc_measurements adc_data = {0}; +#include <stdbool.h> + enum adc_channels { VREF_CH, @@ -26,22 +27,80 @@ enum adc_channels { TEMP_CH, NCH }; -static volatile uint16_t adc_buf[1024]; - -void adc_init(void) { - /* The ADC is used for temperature measurement. To compute the temperature from an ADC reading of the internal - * temperature sensor, the supply voltage must also be measured. Thus we are using two channels. - * - * The ADC is triggered by compare channel 4 of timer 1. The trigger is set to falling edge to trigger on compare - * match, not overflow. - */ - ADC1->CFGR1 = ADC_CFGR1_DMAEN | ADC_CFGR1_DMACFG | (2<<ADC_CFGR1_EXTEN_Pos) | (1<<ADC_CFGR1_EXTSEL_Pos) | ADC_CFGR1_CONT; + +volatile uint16_t adc_buf[ADC_BUFSIZE]; +volatile struct adc_measurements adc_data = {0}; +enum adc_mode adc_mode = ADC_UNINITIALIZED; +int adc_oversampling = 0; + +static void adc_dma_init(int burstlen, bool enable_interrupt); +static void adc_timer_init(int psc, int ivl); + +void adc_configure_scope_mode(uint8_t channel_mask, int sampling_interval_ns) { + /* The constant SAMPLE_FAST (0) when passed in as sampling_interval_ns is handled specially in that we turn the ADC + to continuous mode to get the highest possible sampling rate. */ + + /* First, disable trigger timer, DMA and ADC in case we're reconfiguring on the fly. */ + TIM1->CR1 &= ~TIM_CR1_CEN; + ADC1->CR &= ~ADC_CR_ADSTART; + DMA1_Channel1->CCR &= ~DMA_CCR_EN; /* Enable channel */ + + /* keep track of current mode in global variable */ + adc_mode = ADC_SCOPE; + + adc_dma_init(sizeof(adc_buf)/sizeof(adc_buf[0]), false); + /* Clock from PCLK/4 instead of the internal exclusive high-speed RC oscillator. */ ADC1->CFGR2 = (2<<ADC_CFGR2_CKMODE_Pos); /* Use PCLK/4=12MHz */ /* Sampling time 13.5 ADC clock cycles -> total conversion time 2.17us*/ ADC1->SMPR = (2<<ADC_SMPR_SMP_Pos); - ADC1->CHSELR = ADC_CHSELR_CHSEL0 | ADC_CHSELR_CHSEL1; + /* Setup DMA and triggering */ + if (sampling_interval_ns == SAMPLE_FAST) /* Continuous trigger */ + ADC1->CFGR1 = ADC_CFGR1_DMAEN | ADC_CFGR1_DMACFG | ADC_CFGR1_CONT; + else /* Trigger from timer 1 Channel 4 */ + ADC1->CFGR1 = ADC_CFGR1_DMAEN | ADC_CFGR1_DMACFG | (2<<ADC_CFGR1_EXTEN_Pos) | (1<<ADC_CFGR1_EXTSEL_Pos); + ADC1->CHSELR = channel_mask; + /* Perform self-calibration */ + ADC1->CR |= ADC_CR_ADCAL; + while (ADC1->CR & ADC_CR_ADCAL) + /* Enable conversion */ + ADC1->CR |= ADC_CR_ADSTART; + + if (sampling_interval_ns == SAMPLE_FAST) + return; /* We don't need the timer to trigger in continuous mode. */ + + /* An ADC conversion takes 1.1667us, so to be sure we don't get data overruns we limit sampling to every 1.5us. + Since we don't have a spare PLL to generate the ADC sample clock and re-configuring the system clock just for this + would be overkill we round to 250ns increments. The minimum sampling rate is about 60Hz due to timer resolution. */ + int cycles = sampling_interval_ns > 1500 ? sampling_interval_ns/250 : 6; + if (cycles > 0xffff) + cycles = 0xffff; + adc_timer_init(12/*250ns/tick*/, cycles); +} + +void adc_configure_monitor_mode(int oversampling) { + /* First, disable trigger timer, DMA and ADC in case we're reconfiguring on the fly. */ + TIM1->CR1 &= ~TIM_CR1_CEN; + ADC1->CR &= ~ADC_CR_ADSTART; + DMA1_Channel1->CCR &= ~DMA_CCR_EN; /* Enable channel */ + + /* keep track of current mode in global variable */ + adc_mode = ADC_MONITOR; + adc_oversampling = oversampling; + + adc_dma_init(NCH, true); + + /* Setup DMA and triggering: Trigger from Timer 1 Channel 4 */ + ADC1->CFGR1 = ADC_CFGR1_DMAEN | ADC_CFGR1_DMACFG | (2<<ADC_CFGR1_EXTEN_Pos) | (1<<ADC_CFGR1_EXTSEL_Pos); + /* Clock from PCLK/4 instead of the internal exclusive high-speed RC oscillator. */ + ADC1->CFGR2 = (2<<ADC_CFGR2_CKMODE_Pos); /* Use PCLK/4=12MHz */ + /* Sampling time 13.5 ADC clock cycles -> total conversion time 2.17us*/ + ADC1->SMPR = (2<<ADC_SMPR_SMP_Pos); + /* Internal VCC and temperature sensor channels */ + ADC1->CHSELR = ADC_CHSELR_CHSEL0 | ADC_CHSELR_CHSEL1 | ADC_CHSELR_CHSEL16 | ADC_CHSELR_CHSEL17; + /* Enable internal voltage reference and temperature sensor */ + ADC->CCR = ADC_CCR_TSEN | ADC_CCR_VREFEN; /* Perform ADC calibration */ ADC1->CR |= ADC_CR_ADCAL; while (ADC1->CR & ADC_CR_ADCAL) @@ -50,27 +109,83 @@ void adc_init(void) { ADC1->CR |= ADC_CR_ADEN; ADC1->CR |= ADC_CR_ADSTART; + adc_timer_init(SystemCoreClock/1000000/*1.0us/tick*/, 20/*us*/); +} + +static void adc_dma_init(int burstlen, bool enable_interrupt) { /* Configure DMA 1 Channel 1 to get rid of all the data */ DMA1_Channel1->CPAR = (unsigned int)&ADC1->DR; DMA1_Channel1->CMAR = (unsigned int)&adc_buf; - DMA1_Channel1->CNDTR = sizeof(adc_buf)/sizeof(adc_buf[0]); + DMA1_Channel1->CNDTR = burstlen; DMA1_Channel1->CCR = (0<<DMA_CCR_PL_Pos); DMA1_Channel1->CCR |= DMA_CCR_CIRC /* circular mode so we can leave it running indefinitely */ | (1<<DMA_CCR_MSIZE_Pos) /* 16 bit */ | (1<<DMA_CCR_PSIZE_Pos) /* 16 bit */ | DMA_CCR_MINC - | DMA_CCR_TCIE; /* Enable transfer complete interrupt. */ + | (enable_interrupt ? DMA_CCR_TCIE : 0); /* Enable transfer complete interrupt. */ + + if (enable_interrupt) { + /* triggered on transfer completion. We use this to process the ADC data */ + NVIC_EnableIRQ(DMA1_Channel1_IRQn); + NVIC_SetPriority(DMA1_Channel1_IRQn, 3<<5); + } else { + NVIC_DisableIRQ(DMA1_Channel1_IRQn); + DMA1->IFCR |= DMA_IFCR_CGIF1; + } + DMA1_Channel1->CCR |= DMA_CCR_EN; /* Enable channel */ +} + +static void adc_timer_init(int psc, int ivl) { + TIM1->BDTR = TIM_BDTR_MOE; /* MOE is needed even though we only "output" a chip-internal signal TODO: Verify this. */ + TIM1->CCMR2 = (6<<TIM_CCMR2_OC4M_Pos); /* PWM Mode 1 to get a clean trigger signal */ + TIM1->CCER = TIM_CCER_CC4E; /* Enable capture/compare unit 4 connected to ADC */ + TIM1->CCR4 = 1; /* Trigger at start of timer cycle */ + /* Set prescaler and interval */ + TIM1->PSC = psc-1; + TIM1->ARR = ivl-1; + /* Preload all values */ + TIM1->EGR |= TIM_EGR_UG; + TIM1->CR1 = TIM_CR1_ARPE; + /* And... go! */ + TIM1->CR1 |= TIM_CR1_CEN; - /* triggered on transfer completion. We use this to process the ADC data */ - NVIC_EnableIRQ(DMA1_Channel1_IRQn); - NVIC_SetPriority(DMA1_Channel1_IRQn, 3<<5); } void DMA1_Channel1_IRQHandler(void) { + /* This interrupt takes either 1.2us or 13us. It can be pre-empted by the more timing-critical UART and LED timer + * interrupts. */ + static int count = 0; /* oversampling accumulator sample count */ + static uint32_t adc_aggregate[NCH] = {0}; /* oversampling accumulator */ + /* Clear the interrupt flag */ DMA1->IFCR |= DMA_IFCR_CGIF1; + for (int i=0; i<NCH; i++) + adc_aggregate[i] += adc_buf[i]; + + if (++count == (1<<adc_oversampling)) { + for (int i=0; i<NCH; i++) + adc_aggregate[i] >>= adc_oversampling; + /* This has been copied from the code examples to section 12.9 ADC>"Temperature sensor and internal reference + * voltage" in the reference manual with the extension that we actually measure the supply voltage instead of + * hardcoding it. This is not strictly necessary since we're running off a bored little LDO but it's free and + * the current supply voltage is a nice health value. + */ + adc_data.adc_vcc_mv = (3300 * VREFINT_CAL)/(adc_aggregate[VREF_CH]); + + int64_t read = adc_aggregate[TEMP_CH] * 10 * 10000; + int64_t vcc = adc_data.adc_vcc_mv; + int64_t cal = TS_CAL1 * 10 * 10000; + adc_data.adc_temp_celsius_tenths = 300 + ((read/4096 * vcc) - (cal/4096 * 3300))/43000; + + adc_data.adc_vmeas_a_mv = (adc_aggregate[VMEAS_A]*13300L)/4096 * vcc / 3300; + adc_data.adc_vmeas_b_mv = (adc_aggregate[VMEAS_B]*13300L)/4096 * vcc / 3300; + + count = 0; + for (int i=0; i<NCH; i++) + adc_aggregate[i] = 0; + } } |