{"id":3799,"date":"2021-11-17T11:46:50","date_gmt":"2021-11-17T10:46:50","guid":{"rendered":"https:\/\/www.pschatzmann.ch\/home\/?p=3799"},"modified":"2022-09-25T10:56:28","modified_gmt":"2022-09-25T08:56:28","slug":"using-a-i2s-adc-audio-i2s-capture-card-module-with-an-esp32","status":"publish","type":"post","link":"https:\/\/www.pschatzmann.ch\/home\/2021\/11\/17\/using-a-i2s-adc-audio-i2s-capture-card-module-with-an-esp32\/","title":{"rendered":"Using an ‘I2S HIRES ADC Audio I2S Capture Card Module’ with an ESP32"},"content":{"rendered":"

Quite some time ago I have purchased an Audio Analog to Digital Converter (ADC) module<\/strong>, but I never managed to have it working properly. Unfortunately Google Search could not help either and I was the only one using this module or having problems.<\/p>\n

\"\"<\/p>\n

The Software<\/h2>\n

Finally I have it working now and therefore document my setup in the hope that this might save you some time. Since I am doing all my audio projects with my Arduino Audio Tools Library<\/a>, I first show how to use it there:<\/p>\n

    I2SStream i2sStream; \/\/ Access I2S as stream\n    auto cfg = i2sStream.defaultConfig(RX_MODE);\n    cfg.bits_per_sample = 32;\n    cfg.channels = 2;\n    cfg.sample_rate = 96000;\n    cfg.is_master = false;\n    cfg.i2s_format = I2S_MSB_FORMAT;\n    cfg.use_apll = true;\n    i2sStream.begin(cfg);\n\n<\/code><\/pre>\n
The key to success was to use it in slave mode<\/strong> with a sampling rate<\/strong> of 96000 and of 32 bits per sample<\/strong>. The noise finally disappeared when I activated the APLL<\/strong>!<\/p>\n
The code above roughly translates to the following ESP32 ADF I2S settings:<\/p>\n

    i2s_config_t i2s_config = {\n            .mode = I2S_MODE_SLAVE | I2S_MODE_RX,\n            .sample_rate = 96000,\n            .bits_per_sample = (i2s_bits_per_sample_t) 32,\n            .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,\n            .communication_format = I2S_COMM_FORMAT_STAND_I2S,\n            .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1, \/\/ default interrupt priority\n            .dma_buf_count = 8,\n            .dma_buf_len = 64,\n            .use_apll = true,\n            .tx_desc_auto_clear = true \/\/ avoiding noise in case of data unavailability\n      };\n<\/code><\/pre>\n
The Hardware Connections<\/h2>\n
On the ESP32 the I2S pins are defined in the i2s_pin_config_t structure.<\/p>\n\n\n\n\n\n\n\n\n\n\n
Module<\/th>\nESP32<\/th>\n<\/tr>\n<\/thead>\n
BLCK<\/td>\nbck_io_num (e.g. GPIO14)<\/td>\n<\/tr>\n
DATA<\/td>\ndata_in_num (e.g. GPIO32)<\/td>\n<\/tr>\n
LRCK<\/td>\nws_io_num (e.g.GPIO15)<\/td>\n<\/tr>\n
GND<\/td>\nGND<\/td>\n<\/tr>\n
MUTE<\/td>\n–<\/td>\n<\/tr>\n
VCC<\/td>\n5V<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
Please note that the jumper on the module<\/strong> must be set, so that CLOCK OUT<\/strong> is connecting the MCLK IN<\/strong> pin!
\nThe MUTE pin is pulled high, so it can be floating to produce any output. If you want to control it via a GPIO pin: setting the value to high produces output – low stops output.<\/p>\n
As audio input I was connecting an Apple IPAD<\/strong> to the Audio IN of the ADC module.<\/p>\n
The Result<\/h2>\n
Here is the result from the Arduino Plotter:<\/p>\n
\"\"<\/p>\n
This looks just perfect!<\/p>\n
Unfortunately I did not manage to have this working in master mode: I tried to provide the master frequency with the help of the apll<\/p>\n