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I2s adc (#2309)

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* An example to read high frequency analog data using i2s_adc

* HiFreq_ADC.ino
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lbernstone 2019-01-22 02:24:16 -07:00 committed by Me No Dev
parent 6718da0350
commit fa6f75952d
1 changed files with 25 additions and 13 deletions
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38
libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino
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@ -1,7 +1,7 @@
/* /*
* This is an example to read analog data at high frequency using the I2S peripheral * This is an example to read analog data at high frequency using the I2S peripheral
* Run a wire between pins 27 & 32 * Run a wire between pins 27 & 32
* The readings from the device will be 12bit (0-4096) * The readings from the device will be 12bit (0-4096)
*/ */
#include <driver/i2s.h> #include <driver/i2s.h>
@ -9,7 +9,9 @@
#define ADC_INPUT ADC1_CHANNEL_4 //pin 32 #define ADC_INPUT ADC1_CHANNEL_4 //pin 32
#define OUTPUT_PIN 27 #define OUTPUT_PIN 27
#define OUTPUT_VALUE 3800 #define OUTPUT_VALUE 3800
#define READ_DELAY 10000 //microseconds #define READ_DELAY 9000 //microseconds
uint16_t adc_reading;
void i2sInit() void i2sInit()
{ {
@ -34,23 +36,29 @@ void i2sInit()
void reader(void *pvParameters) { void reader(void *pvParameters) {
uint32_t read_counter = 0; uint32_t read_counter = 0;
uint64_t read_sum = 0; uint64_t read_sum = 0;
// The 4 high bits are the channel, and the data is inverted
uint16_t offset = (int)ADC_INPUT * 0x1000 + 0xFFF;
size_t bytes_read;
while(1){ while(1){
size_t bytes_read = 0; uint16_t buffer[2] = {0};
uint16_t buffer = 0; i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, 15);
i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, portMAX_DELAY); //Serial.printf("%d %d\n", offset - buffer[0], offset - buffer[1]);
buffer = ~buffer; // The data is inverted if (bytes_read == sizeof(buffer)) {
//Serial.println(buffer % 0x1000); read_sum += offset - buffer[0];
read_sum += buffer % 0x1000; // The 4 high bits are the channel read_sum += offset - buffer[1];
read_counter++; read_counter++;
if (bytes_read != sizeof(buffer)) Serial.println("buffer empty!"); } else {
Serial.println("buffer empty");
}
if (read_counter == I2S_SAMPLE_RATE) { if (read_counter == I2S_SAMPLE_RATE) {
Serial.printf("avg: %d\n", read_sum/I2S_SAMPLE_RATE); adc_reading = read_sum / I2S_SAMPLE_RATE / 2;
//Serial.printf("avg: %d millis: ", adc_reading);
//Serial.println(millis());
read_counter = 0; read_counter = 0;
read_sum = 0; read_sum = 0;
i2s_adc_disable(I2S_NUM_0); i2s_adc_disable(I2S_NUM_0);
delay(READ_DELAY); delay(READ_DELAY);
i2s_adc_enable(I2S_NUM_0); i2s_adc_enable(I2S_NUM_0);
} }
} }
} }
@ -68,4 +76,8 @@ void setup() {
xTaskCreatePinnedToCore(reader, "ADC_reader", 2048, NULL, 1, NULL, 1); xTaskCreatePinnedToCore(reader, "ADC_reader", 2048, NULL, 1, NULL, 1);
} }
void loop() {} void loop() {
delay(1020);
Serial.printf("ADC reading: %d\n", adc_reading);
delay(READ_DELAY);
}