From d8662d59a077dfcf88a2bbd1cff4b7db4ed67068 Mon Sep 17 00:00:00 2001 From: Larry Bernstone Date: Wed, 9 Jan 2019 21:28:41 -0700 Subject: [PATCH 1/2] An example to read high frequency analog data using i2s_adc --- .../examples/I2S/HiFreq_ADC/HiFreq_ADC.ino | 71 +++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100644 libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino diff --git a/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino b/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino new file mode 100644 index 00000000000..83538db59bb --- /dev/null +++ b/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino @@ -0,0 +1,71 @@ +/* + * 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 + +#define I2S_SAMPLE_RATE 78125 +#define ADC_INPUT ADC1_CHANNEL_4 //pin 32 +#define OUTPUT_PIN 27 +#define OUTPUT_VALUE 3800 +#define READ_DELAY 10000 //microseconds + +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, // The format of the signal using ADC_BUILT_IN + .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT, // is fixed at 12bit, stereo, MSB + .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; + while(1){ + size_t bytes_read = 0; + uint16_t buffer = 0; + i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, portMAX_DELAY); + buffer = ~buffer; // The data is inverted + //Serial.println(buffer % 0x1000); + read_sum += buffer % 0x1000; // The 4 high bits are the channel + read_counter++; + if (bytes_read != sizeof(buffer)) Serial.println("buffer empty!"); + if (read_counter == I2S_SAMPLE_RATE) { + Serial.printf("avg: %d\n", read_sum/I2S_SAMPLE_RATE); + 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); + // Put a signal out on pin + uint32_t freq = ledcSetup(0, I2S_SAMPLE_RATE, 10); + Serial.printf("Output frequency: %d\n", freq); + ledcWrite(0, OUTPUT_VALUE/4); + ledcAttachPin(OUTPUT_PIN, 0); + // Initialize the I2S peripheral + i2sInit(); + // Create a task that will read the data + xTaskCreatePinnedToCore(reader, "ADC_reader", 2048, NULL, 1, NULL, 1); +} + +void loop() {} From 8db7ea26fb82f28533b901d439b1d81948ebcd90 Mon Sep 17 00:00:00 2001 From: Larry Bernstone Date: Fri, 11 Jan 2019 14:50:56 -0700 Subject: [PATCH 2/2] HiFreq_ADC.ino --- .../examples/I2S/HiFreq_ADC/HiFreq_ADC.ino | 38 ++++++++++++------- 1 file changed, 25 insertions(+), 13 deletions(-) diff --git a/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino b/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino index 83538db59bb..df328d1d6b1 100644 --- a/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino +++ b/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino @@ -1,7 +1,7 @@ /* * 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) + * The readings from the device will be 12bit (0-4096) */ #include @@ -9,7 +9,9 @@ #define ADC_INPUT ADC1_CHANNEL_4 //pin 32 #define OUTPUT_PIN 27 #define OUTPUT_VALUE 3800 -#define READ_DELAY 10000 //microseconds +#define READ_DELAY 9000 //microseconds + +uint16_t adc_reading; void i2sInit() { @@ -34,23 +36,29 @@ void i2sInit() void reader(void *pvParameters) { uint32_t read_counter = 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){ - size_t bytes_read = 0; - uint16_t buffer = 0; - i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, portMAX_DELAY); - buffer = ~buffer; // The data is inverted - //Serial.println(buffer % 0x1000); - read_sum += buffer % 0x1000; // The 4 high bits are the channel - read_counter++; - if (bytes_read != sizeof(buffer)) Serial.println("buffer empty!"); + uint16_t buffer[2] = {0}; + i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, 15); + //Serial.printf("%d %d\n", offset - buffer[0], offset - buffer[1]); + 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) { - 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_sum = 0; i2s_adc_disable(I2S_NUM_0); delay(READ_DELAY); i2s_adc_enable(I2S_NUM_0); - } } } @@ -68,4 +76,8 @@ void setup() { 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); +}