72 lines
2.2 KiB
Arduino
72 lines
2.2 KiB
Arduino
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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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*/
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#include <driver/i2s.h>
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#define I2S_SAMPLE_RATE 78125
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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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void i2sInit()
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{
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i2s_config_t i2s_config = {
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.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN),
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.sample_rate = I2S_SAMPLE_RATE, // The format of the signal using ADC_BUILT_IN
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.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT, // is fixed at 12bit, stereo, MSB
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.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
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.communication_format = I2S_COMM_FORMAT_I2S_MSB,
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.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
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.dma_buf_count = 4,
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.dma_buf_len = 8,
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.use_apll = false,
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.tx_desc_auto_clear = false,
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.fixed_mclk = 0
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};
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i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
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i2s_set_adc_mode(ADC_UNIT_1, ADC_INPUT);
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i2s_adc_enable(I2S_NUM_0);
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}
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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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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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if (read_counter == I2S_SAMPLE_RATE) {
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Serial.printf("avg: %d\n", read_sum/I2S_SAMPLE_RATE);
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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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void setup() {
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Serial.begin(115200);
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// Put a signal out on pin
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uint32_t freq = ledcSetup(0, I2S_SAMPLE_RATE, 10);
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Serial.printf("Output frequency: %d\n", freq);
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ledcWrite(0, OUTPUT_VALUE/4);
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ledcAttachPin(OUTPUT_PIN, 0);
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// Initialize the I2S peripheral
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i2sInit();
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// Create a task that will read the data
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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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