diff options
Diffstat (limited to 'controller/fw/src/adc.c')
| -rw-r--r-- | controller/fw/src/adc.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/controller/fw/src/adc.c b/controller/fw/src/adc.c new file mode 100644 index 0000000..5f6b995 --- /dev/null +++ b/controller/fw/src/adc.c @@ -0,0 +1,93 @@ + +#include <stm32f407xx.h> +#include <stm32f4_isr.h> + +#include "adc.h" +#include "sr_global.h" + +uint16_t adc_fft_buf[2][FMEAS_FFT_LEN]; +volatile int adc_fft_buf_ready_idx = -1; + +static DMA_TypeDef *const adc_dma = DMA2; +static DMA_Stream_TypeDef *const mem_stream = DMA2_Stream1; +static DMA_Stream_TypeDef *const adc_stream = DMA2_Stream0; +static const int dma_adc_channel = 0; + +/* Configure ADC1 to sample channel 0. Trigger from TIM1 CC0 every 1ms. Transfer readings into alternating buffers + * throug DMA. Enable DMA interrupts. + * + * We have two full FFT buffers. We always transfer data from the ADC to the back half of the active one, while a + * DMA memcpy'es the latter half of the inactive one to the front half of the active one. This means at the end of the + * ADC's DMA transfer, in the now-inactive buffer that the ADC results were just written to we have last half-period's + * data sitting in front of this half-period's data like so: [old_adc_data, new_adc_data] + * + * This means we can immediately start running an FFT on ADC DMA transfer complete interrupt. + */ +void adc_init() { + RCC->AHB1ENR |= RCC_AHB1ENR_DMA2EN; + RCC->APB2ENR |= RCC_APB2ENR_ADC1EN | RCC_APB2ENR_TIM1EN; + + adc_dma->LIFCR |= 0x3f; + adc_stream->CR = 0; /* disable */ + while (adc_stream->CR & DMA_SxCR_EN) + ; /* wait for stream to become available */ + adc_stream->NDTR = FMEAS_FFT_LEN/2; + adc_stream->PAR = ADC1->DR; + adc_stream->M0AR = (uint32_t) (adc_fft_buf[0] + FMEAS_FFT_LEN/2); + adc_stream->M1AR = (uint32_t) (adc_fft_buf[1] + FMEAS_FFT_LEN/2); + adc_stream->CR = (dma_adc_channel<<DMA_SxCR_CHSEL_Pos) | DMA_SxCR_DBM | (1<<DMA_SxCR_MSIZE_Pos) + | (1<<DMA_SxCR_PSIZE_Pos) | DMA_SxCR_MINC | DMA_SxCR_CIRC | DMA_SxCR_PFCTRL + | DMA_SxCR_TCIE | DMA_SxCR_TEIE | DMA_SxCR_DMEIE | DMA_SxCR_EN; + adc_stream->CR |= DMA_SxCR_EN; + + NVIC_EnableIRQ(DMA2_Stream0_IRQn); + NVIC_SetPriority(DMA2_Stream0_IRQn, 128); + + ADC1->CR1 = (0<<ADC_CR1_RES_Pos) | (0<<ADC_CR1_DISCNUM_Pos) | ADC_CR1_DISCEN | (0<<ADC_CR1_AWDCH_Pos); + ADC1->CR2 = ADC_CR2_EXTEN | (0<<ADC_CR2_EXTSEL_Pos) | ADC_CR2_DMA | ADC_CR2_ADON | ADC_CR2_DDS; + + TIM1->CR2 = (2<<TIM_CR2_MMS_Pos); /* Enable update event on TRGO to provide a 1ms reference to rest of system */ + TIM1->CR1 = TIM_CR1_CEN; + TIM1->CCMR1 = (6<<TIM_CCMR1_OC1M_Pos) | (0<<TIM_CCMR1_CC1S_Pos); + TIM1->CCER = TIM_CCER_CC1E; + TIM1->PSC = 84; /* 1us ticks @ f_APB2=84MHz */ + TIM1->ARR = 1000; /* 1ms period */ + TIM1->CCR1 = 1; + TIM1->EGR = TIM_EGR_UG; +} + +void DMA2_Stream0_IRQHandler(void) { + uint8_t isr = (DMA2->LISR >> DMA_LISR_FEIF0_Pos) & 0x3f; + + if (isr & DMA_LISR_TCIF0) { /* Transfer complete */ + /* Check we're done processing the old buffer */ + if (adc_fft_buf_ready_idx != -1) + panic(); + + /* Kickoff memory DMA into new buffer */ + if (mem_stream->CR & DMA_SxCR_EN) + panic(); /* We should be long done by now. */ + + mem_stream->NDTR = FMEAS_FFT_LEN/2; + int ct = !!(adc_stream->CR & DMA_SxCR_CT); + /* back half of old buffer (that was just written) */ + mem_stream->PAR = (uint32_t)(adc_fft_buf[!ct]); + /* front half of current buffer (whose back half is being written now) */ + mem_stream->M0AR = (uint32_t) (adc_fft_buf[ct] + 0); + mem_stream->CR = (1<<DMA_SxCR_MSIZE_Pos) | (1<<DMA_SxCR_PSIZE_Pos) | DMA_SxCR_MINC | DMA_SxCR_PINC + | DMA_SxCR_TCIE | DMA_SxCR_TEIE | DMA_SxCR_DMEIE; + mem_stream->CR |= DMA_SxCR_EN; + + /* Kickoff FFT */ + adc_fft_buf_ready_idx = !ct; + } + + if (isr & DMA_LISR_DMEIF0) /* Direct mode error */ + panic(); + + if (isr & DMA_LISR_TEIF0) /* Transfer error */ + panic(); + + /* clear all flags */ + adc_dma->LIFCR = isr<<DMA_LISR_FEIF0_Pos; +} |