ESP32 Configuration

If you are using ESP32 by Espressif Systems version 3.0.0 and later, audio tools will use the new adc_continuous API. This board option is under development and changing.

For the adc_continuous API, audio tools provides the following options:

sample_rate (per channel), the effective ADC sampling rate is the number of channels x sample rate and can be:
- ESP32: 20kHz to 2MHz
- other ESP32 eg. ESP32S3 611Hz to 83kHz

for example:

-       306
-     4,000
-     5,000
-     8,000
-    10,000
-    11,025
-    16,000
-    20,000
-    22,050
-    40,000
-    44,100
-    48,000
-    88,200
-    96,000
-   176,400
-   192,200
-   352,800
-   384,000
-   500,000
- 1,000,000

adc_bit_with
- 9, 10, 11, 12 depending on ESP32 model
- audio stream is int16_t
adc_calibration_active: values measured are in mV
is_auto_center_read: subtraction of current estimated average from samples
adc_attenuation:

attenuation range accurate range

ADC_ATTEN_DB_0 0..1.1V 100-950mV

ADC_ATTEN_DB_2_5 0..1.5V 100-1250mV

ADC_ATTEN_DB_6 0..2.2V 150-1750mV

ADC_ATTEN_DB_12 0..3.9V 150-2450mV
channels:
- mono = 1
- stereo = 2
adc_channels: defining the channels (only channels on ADC unit 1 are supported) e.g.:
- A3 on Sparkfun ESP32 Thing Plus is ADC_CHANNEL_3
- A4 on Sparkfun ESP32 Thing Plus is ADC_CHANNEL_0
- D5 on Adafruit ESP32-S3 is ADC_CHANNEL_4
- D6 on Adafruit ESP32-S3 is ADC_CHANNEL_5

attenuation	range	accurate range
ADC_ATTEN_DB_0	0..1.1V	100-950mV
ADC_ATTEN_DB_2_5	0..1.5V	100-1250mV
ADC_ATTEN_DB_6	0..2.2V	150-1750mV
ADC_ATTEN_DB_12	0..3.9V	150-2450mV

Example Configuration

auto adcConfig = adc.defaultConfig(RX_MODE);
adcConfig.sample_rate = 44100;
adcConfig.adc_bit_width = 12;
adcConfig.adc_calibration_active = true;
adcConfig.is_auto_center_read = false;
adcConfig.adc_attenuation = ADC_ATTEN_DB_12; 
adcConfig.channels = 2;
adcConfig.adc_channels[0] = ADC_CHANNEL_4; 
adcConfig.adc_channels[1] = ADC_CHANNEL_5;

ADC unit 1 channels on common ESP32 boards

Audio tools supports ADC Unit 1 only.

Sparkfun ESP32 Thing Plus (ESP32)

A2, ADC1_CH6
A3, ADC1_CH3
A4, ADC1_CH0
32, ADC1_CH4
33, ADC1_CH5

Sparkfun ESP32 Qwiic Pocket Development (ESP32C6)

2, ADC1_CH2
3, ADC1_CH3
4, ADC1_CH4
5, ADC1_CH5

ESP32-C6-DevKit

4, ADC1_CH4
5, ADC1_CH5
6, ADC1_CH6
7, ADC1_CH0
0, ADC1_CH1
2, ADC1_CH2
3, ADC1_CH3

ESP32-H2-DevKit

1, ADC1_CH0
2, ADC1_CH1
3, ADC1_CH2
4, ADC1_CH3
5, ADC1_CH4

ESP32-S3-DevKit

1, ADC1_CH0
2, ADC1_CH1
4, ADC1_CH3
5, ADC1_CH4
6, ADC1_CH5
7, ADC1_CH6
8, ADC1_CH7
3, ADC1_CH2
9, ADC1_CH8
10, ADC1_CH9

ESP32-C3-DevKit

4, IO2, ADC1_CH2
5, IO3, ADC1_CH3
9, IO0, ADC1_CH0
10, IO1, ADC1_CH1
11, IO4, ADC1_CH4

Adafruit ESP32 Feather V2

D32, ADC1_CH4
D33, ADC1_CH5
A2, ADC1_CH6
A3, ADC1_CH3
A4, ADC1_CH0
D37, ADC1_CH1

Adafruit ESP32-S3 Feather

D5, ADC1_CH4
D6, ADC1_CH5
D9, ADC1_CH8
D10, ADC1_CH9
A5, ADC1_CH7

Adafruit QT Py ESP32-C3

A0, ADC1-CH4
A1, ADC1-CH3
A2, ADC1-CH1
A3, ADC1-CH0

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