I2S setup

main1.c

nrf_drv_i2s_config_t config = NRF_DRV_I2S_DEFAULT_CONFIG;
config.sdin_pin  = I2S_SDIN_PIN;
config.sdout_pin = I2S_SDOUT_PIN;
config.mck_setup = NRF_I2S_MCK_32MDIV10; ///< 32 MHz / 10 = 3.2 MHz.
config.ratio     = NRF_I2S_RATIO_32X;    ///< LRCK = MCK / 32.
config.channels  = NRF_I2S_CHANNELS_STEREO;

err_code = nrf_drv_i2s_init(&config, data_handler);
APP_ERROR_CHECK(err_code);