initial commit

2026-09-25 10:48:51 +10:00
commit b90beea8ae
1020 changed files with 131665 additions and 0 deletions
@@ -0,0 +1,112 @@
+#include <Adafruit_ZeroDMA.h>
+
+#define ADC_PIN A4
+#define SAMPLE_BLOCK_LENGTH 256
+
+Adafruit_ZeroDMA ADC_DMA;
+DmacDescriptor *dmac_descriptor_1;
+DmacDescriptor *dmac_descriptor_2;
+
+uint16_t adc_buffer[SAMPLE_BLOCK_LENGTH * 2];
+uint16_t adc_sample_block[SAMPLE_BLOCK_LENGTH];
+volatile bool filling_first_half = true;
+volatile uint16_t *active_adc_buffer;
+volatile bool adc_buffer_filled = false;
+
+
+uint16_t peak_to_peak(uint16_t *data, int data_length){
+  int signalMax = 0;
+  int signalMin = 4096;  // max value for 12 bit adc
+ 
+  for(int i=0; i<data_length; i++){
+    if ( data[i] > signalMax ) {
+      signalMax = data[i];
+    }
+    if (data[i] < signalMin ){
+      signalMin = data[i];
+    }
+  }
+  return signalMax - signalMin;
+}
+
+
+void dma_callback(Adafruit_ZeroDMA *dma) {
+  (void) dma;
+  if (filling_first_half) {
+    // DMA is filling the first half of the buffer, use data from the second half
+    active_adc_buffer = &adc_buffer[SAMPLE_BLOCK_LENGTH];
+    filling_first_half = false;
+  } else {
+    // DMA is filling the second half of the buffer, use data from the first half
+    active_adc_buffer = &adc_buffer[0];
+    filling_first_half = true;
+  }
+  adc_buffer_filled = true;
+}
+
+
+static void ADCsync() {
+  while (ADC->STATUS.bit.SYNCBUSY == 1);
+}
+
+
+void adc_init() {
+  analogRead(ADC_PIN);
+  ADC->CTRLA.bit.ENABLE = 0;
+  ADCsync();
+  ADC->INPUTCTRL.bit.GAIN = ADC_INPUTCTRL_GAIN_DIV2;
+  ADC->REFCTRL.bit.REFSEL = ADC_REFCTRL_REFSEL_INTVCC1;
+  ADCsync();
+  ADC->INPUTCTRL.bit.MUXPOS = g_APinDescription[ADC_PIN].ulADCChannelNumber;
+  ADCsync();
+  ADC->AVGCTRL.reg = 0;
+  ADC->SAMPCTRL.reg = 2;
+  ADCsync();
+  ADC->CTRLB.reg = ADC_CTRLB_PRESCALER_DIV32 | ADC_CTRLB_FREERUN | ADC_CTRLB_RESSEL_12BIT;
+  ADCsync();
+  ADC->CTRLA.bit.ENABLE = 1;
+  ADCsync();
+}
+
+void dma_init(){
+  ADC_DMA.allocate();
+  ADC_DMA.setTrigger(ADC_DMAC_ID_RESRDY);
+  ADC_DMA.setAction(DMA_TRIGGER_ACTON_BEAT);
+  dmac_descriptor_1 = ADC_DMA.addDescriptor(
+           (void *)(&ADC->RESULT.reg),
+           adc_buffer,
+           SAMPLE_BLOCK_LENGTH,
+           DMA_BEAT_SIZE_HWORD,
+           false,
+           true);
+  dmac_descriptor_1->BTCTRL.bit.BLOCKACT = DMA_BLOCK_ACTION_INT;
+
+  dmac_descriptor_2 = ADC_DMA.addDescriptor(
+           (void *)(&ADC->RESULT.reg),
+           adc_buffer + SAMPLE_BLOCK_LENGTH,
+           SAMPLE_BLOCK_LENGTH,
+           DMA_BEAT_SIZE_HWORD,
+           false,
+           true);
+  dmac_descriptor_2->BTCTRL.bit.BLOCKACT = DMA_BLOCK_ACTION_INT;
+
+  ADC_DMA.loop(true);
+  ADC_DMA.setCallback(dma_callback);
+}
+
+
+void setup() {
+  Serial.begin(115200);
+  adc_init();
+  dma_init();
+  ADC_DMA.startJob();
+}
+
+
+void loop() {
+  if(adc_buffer_filled){
+    adc_buffer_filled=false;
+    memcpy(adc_sample_block, (const void*)active_adc_buffer, SAMPLE_BLOCK_LENGTH*sizeof(uint16_t));
+    Serial.println(peak_to_peak(adc_sample_block, SAMPLE_BLOCK_LENGTH));
+  }
+}