I2s adc (#2309)
* An example to read high frequency analog data using i2s_adc * HiFreq_ADC.ino
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@ -1,7 +1,7 @@
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/*
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* This is an example to read analog data at high frequency using the I2S peripheral
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* Run a wire between pins 27 & 32
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* The readings from the device will be 12bit (0-4096)
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* The readings from the device will be 12bit (0-4096)
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*/
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#include <driver/i2s.h>
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@ -9,7 +9,9 @@
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#define ADC_INPUT ADC1_CHANNEL_4 //pin 32
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#define OUTPUT_PIN 27
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#define OUTPUT_VALUE 3800
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#define READ_DELAY 10000 //microseconds
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#define READ_DELAY 9000 //microseconds
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uint16_t adc_reading;
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void i2sInit()
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{
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@ -34,23 +36,29 @@ void i2sInit()
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void reader(void *pvParameters) {
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uint32_t read_counter = 0;
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uint64_t read_sum = 0;
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// The 4 high bits are the channel, and the data is inverted
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uint16_t offset = (int)ADC_INPUT * 0x1000 + 0xFFF;
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size_t bytes_read;
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while(1){
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size_t bytes_read = 0;
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uint16_t buffer = 0;
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i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, portMAX_DELAY);
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buffer = ~buffer; // The data is inverted
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//Serial.println(buffer % 0x1000);
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read_sum += buffer % 0x1000; // The 4 high bits are the channel
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read_counter++;
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if (bytes_read != sizeof(buffer)) Serial.println("buffer empty!");
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uint16_t buffer[2] = {0};
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i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, 15);
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//Serial.printf("%d %d\n", offset - buffer[0], offset - buffer[1]);
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if (bytes_read == sizeof(buffer)) {
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read_sum += offset - buffer[0];
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read_sum += offset - buffer[1];
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read_counter++;
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} else {
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Serial.println("buffer empty");
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}
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if (read_counter == I2S_SAMPLE_RATE) {
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Serial.printf("avg: %d\n", read_sum/I2S_SAMPLE_RATE);
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adc_reading = read_sum / I2S_SAMPLE_RATE / 2;
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//Serial.printf("avg: %d millis: ", adc_reading);
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//Serial.println(millis());
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read_counter = 0;
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read_sum = 0;
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i2s_adc_disable(I2S_NUM_0);
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delay(READ_DELAY);
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i2s_adc_enable(I2S_NUM_0);
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}
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}
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}
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@ -68,4 +76,8 @@ void setup() {
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xTaskCreatePinnedToCore(reader, "ADC_reader", 2048, NULL, 1, NULL, 1);
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}
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void loop() {}
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void loop() {
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delay(1020);
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Serial.printf("ADC reading: %d\n", adc_reading);
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delay(READ_DELAY);
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}
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