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- /*
- This is an example to read analog data at high frequency using the I2S peripheral
- Run a wire between pins 27 & 32
- The readings from the device will be 12bit (0-4096)
- */
- #include <driver/i2s.h>
- #define I2S_SAMPLE_RATE 5000
- #define ADC_INPUT ADC1_CHANNEL_4 //pin 32
- #define READ_DELAY 1000
- uint16_t adc_reading;
- //-------------------------------------------------------------------------------------------------
- void i2sInit()
- {
- i2s_config_t i2s_config = {
- .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN),
- .sample_rate = I2S_SAMPLE_RATE,
- .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
- .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
- .communication_format = I2S_COMM_FORMAT_I2S_MSB,
- .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
- .dma_buf_count = 4,
- .dma_buf_len = 8,
- .use_apll = false,
- .tx_desc_auto_clear = false,
- .fixed_mclk = 0
- };
- i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
- i2s_set_adc_mode(ADC_UNIT_1, ADC_INPUT);
- i2s_adc_enable(I2S_NUM_0);
- }
- //-------------------------------------------------------------------------------------------------
- void reader(void *pvParameters) {
- uint32_t read_counter = 0;
- uint64_t read_sum = 0;
- uint16_t offset = (int)ADC_INPUT * 0x1000 + 0xFFF;
- size_t bytes_read;
- while (1)
- {
- uint16_t buffer[2] = {0};
- i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, 15);
- if (bytes_read == sizeof(buffer)) {
- read_sum += offset - buffer[0];
- read_sum += offset - buffer[1];
- read_counter++;
- }
- else
- {
- Serial.println("buffer empty");
- }
- if (read_counter == I2S_SAMPLE_RATE) {
- adc_reading = read_sum / I2S_SAMPLE_RATE / 2;
- read_counter = 0;
- read_sum = 0;
- i2s_adc_disable(I2S_NUM_0);
- delay(READ_DELAY);
- i2s_adc_enable(I2S_NUM_0);
- }
- }
- }
- //-------------------------------------------------------------------------------------------------
- void setup() {
- Serial.begin(115200);
- i2sInit();
- // Create a task that will read the data
- xTaskCreatePinnedToCore(reader, "ADC_reader", 2048, NULL, 1, NULL, 1);
- }
- //-------------------------------------------------------------------------------------------------
- void loop() {
- Serial.printf("ADC reading: %d\n", adc_reading);
- delay(READ_DELAY);
- }
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