用 FireBeetle P4 做一个 USB 麦克风

void init_pdm_rx(void) {
    i2s_chan_config_t chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM_0, I2S_ROLE_MASTER);
    i2s_new_channel(&chan_cfg, NULL, &rx);

    i2s_pdm_rx_config_t pdm_cfg = {
        .clk_cfg = I2S_PDM_RX_CLK_DEFAULT_CONFIG(CONFIG_UAC_SAMPLE_RATE),
        //.slot_cfg = I2S_PDM_RX_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),
        .slot_cfg = I2S_PDM_RX_SLOT_PCM_FMT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),
                .gpio_cfg = {
            .clk = MIC_I2S_CLK,      // PDM clock
            // QUESTION - what about the LR clock pin? No longer relevant? Do we ties it high or low?
            .din = MIC_I2S_DATA,     // PDM data
            .invert_flags = { .clk_inv = false },
        },
    };
    pdm_cfg.slot_cfg.slot_mode = I2S_SLOT_MODE_MONO; // single mic

    i2s_channel_init_pdm_rx_mode(rx, &pdm_cfg);
    i2s_channel_enable(rx);
}
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static esp_err_t usb_uac_device_input_cb(uint8_t *buf, size_t len, size_t *bytes_read, void *arg)
{
    if (!rx) {
        return ESP_FAIL;
    }
        //memcpy(buf,Buff,len);
        //*bytes_read=len;
        //return ESP_OK;
    return i2s_channel_read(rx, buf, len, bytes_read, portMAX_DELAY);
}
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P4usbmiC.zip