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#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;
}
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