Audio clocking?

[kf6gpe]

Maybe I'm missing something obvious -- it wouldn't be the first time --- but how, if at all, does TinyUSB manage audio clocking?

I see that the SOF isn't supported, and I don't see a lot of information in audio_driver.c. Does anyone have any light to share?

Thanks in advance...

PS: Once I got over my chip-level integration problems that I posted a while ago and got done futzing with some descriptors, integration into our custom project wasn't bad at all! Very cool. Appreciate all of the work done by folks here.

[HiFiPhile]

but how, if at all, does TinyUSB manage audio clocking?

Short answer is no. Due to complicity of audio clocking, there is no way to managing it.

Longer answer is you can refer to uac2_headset example, in the tud_audio_clock_set_request() callback you have the current sample rate, you need to configurate I2S clock accordingly.

Here is a stripped-down of my implementation:

// Helper for clock set requests
static bool tud_audio_clock_set_request(uint8_t rhport, audio_control_request_t const* request, uint8_t const* buf)
{
    (void)rhport;

    TU_VERIFY(request->bEntityID == UAC2_ENTITY_USB2IIS_CLOCK);
    TU_VERIFY(request->bRequest == AUDIO_CS_REQ_CUR);

    if(request->bControlSelector == AUDIO_CS_CTRL_SAM_FREQ)
    {
        TU_VERIFY(request->wLength == sizeof(audio_control_cur_4_t));

        current_sample_rate = ((audio_control_cur_4_t*)buf)->bCur;

        TU_LOG1("Clock set current freq: %d\r\n", current_sample_rate);

        return true;
    }
    else
    {
        TU_LOG1("Clock set request not supported, entity = %u, selector = %u, request = %u\r\n",
                request->bEntityID, request->bControlSelector, request->bRequest);
        return false;
    }
}

bool tud_audio_set_itf_cb(uint8_t rhport, tusb_control_request_t const* p_request)
{
    (void)rhport;
    uint8_t const itf = tu_u16_low(tu_le16toh(p_request->wIndex));
    uint8_t const alt = tu_u16_low(tu_le16toh(p_request->wValue));

    // Clear buffer when streaming format is changed
    if(itf == ITF_NUM_AUDIO_STREAMING_IIS)
    {
        if(alt != 0)
        {
            current_resolution = resolutions_per_format[alt - 1];
            current_bytes_per_sample = bytes_per_sample[alt - 1];
            // Set I2S params
            UAC_Config_Cb(0, current_sample_rate, current_bytes_per_sample, current_resolution);
        }
        else
        {
            UAC_Config_Cb(0, 0, 0, 0);
        }
    }
    return true;
}

/* Called when streaming format is changed */
void UAC_Config_Cb(uint8_t Func, uint32_t SampleRate, uint8_t BytesPerSample, uint8_t Resolution)
{
    if(Func == 0)
    {
        if(current_SampleRate == SampleRate && current_BytesPerSample == BytesPerSample && current_Resolution == Resolution)
        {
            return;
        }

        current_SampleRate = SampleRate;
        current_BytesPerSample = BytesPerSample;
        current_Resolution = Resolution;
        bPlayback_En = current_SampleRate != 0;

        if(SampleRate)
        {
            if((SampleRate % 44100) == 0)
            {
                // For 44.1kHz, 88.2kHz, etc.
                MCLK_Set(MCLK_45_1584M);
                // Set I2S clock divider, DIV = 1 for 352.8k ... DIV = 8 for 44.1k
                I2S_Tx_Init(44100 * 8 / SampleRate,);
            }
            else
            {
                // For 48kHz, 96kHz, etc.
                MCLK_Set(MCLK_49_152M);
                // Set I2S clock divider, DIV = 1 for 384k ... DIV = 8 for 48k
                I2S_Tx_Init(48000 * 8 / SampleRate,);
            }
        }
    }
}

[kf6gpe]

Excellent, thank you!! That was about what I thought, and I just discovered that sample too. Clocking in our product should be interesting, then. We're kicking around ideas now. :) Ray Rischpater, KF6GPE | kf6gpe.org | @kf6gpe <http://www.twitter.com/kf6gpe>

…

On Mon, Apr 17, 2023 at 2:40 AM HiFiPhile ***@***.***> wrote: but how, if at all, does TinyUSB manage audio clocking? Short answer is no. Due to complicity of audio clocking, there is no way to managing it. Longer answer is you can refer to uac2_headset example, in the tud_audio_clock_set_request() callback you have the current sample rate, you need to configurate I2S clock accordingly. Here is a stripped-down of my implementation: // Helper for clock set requestsstatic bool tud_audio_clock_set_request(uint8_t rhport, audio_control_request_t const* request, uint8_t const* buf) { (void)rhport; TU_VERIFY(request->bEntityID == UAC2_ENTITY_USB2IIS_CLOCK); TU_VERIFY(request->bRequest == AUDIO_CS_REQ_CUR); if(request->bControlSelector == AUDIO_CS_CTRL_SAM_FREQ) { TU_VERIFY(request->wLength == sizeof(audio_control_cur_4_t)); current_sample_rate = ((audio_control_cur_4_t*)buf)->bCur; TU_LOG1("Clock set current freq: %d\r\n", current_sample_rate); return true; } else { TU_LOG1("Clock set request not supported, entity = %u, selector = %u, request = %u\r\n", request->bEntityID, request->bControlSelector, request->bRequest); return false; } } bool tud_audio_set_itf_cb(uint8_t rhport, tusb_control_request_t const* p_request) { (void)rhport; uint8_t const itf = tu_u16_low(tu_le16toh(p_request->wIndex)); uint8_t const alt = tu_u16_low(tu_le16toh(p_request->wValue)); // Clear buffer when streaming format is changed if(itf == ITF_NUM_AUDIO_STREAMING_IIS) { if(alt != 0) { current_resolution = resolutions_per_format[alt - 1]; current_bytes_per_sample = bytes_per_sample[alt - 1]; // Set I2S params UAC_Config_Cb(0, current_sample_rate, current_bytes_per_sample, current_resolution); } else { UAC_Config_Cb(0, 0, 0, 0); } } return true; } /* Called when streaming format is changed */void UAC_Config_Cb(uint8_t Func, uint32_t SampleRate, uint8_t BytesPerSample, uint8_t Resolution) { if(Func == 0) { if(current_SampleRate == SampleRate && current_BytesPerSample == BytesPerSample && current_Resolution == Resolution) { return; } current_SampleRate = SampleRate; current_BytesPerSample = BytesPerSample; current_Resolution = Resolution; bPlayback_En = current_SampleRate != 0; if(SampleRate) { bool spdif_En = SampleRate < 192000; if((SampleRate % 44100) == 0) { MCLK_Set(MCLK_45_1584M); I2S_Tx_Init(1, 44100 * 8 / SampleRate, spdif_En); } else { MCLK_Set(MCLK_49_152M); I2S_Tx_Init(1, 48000 * 8 / SampleRate, spdif_En); } bSPDIF_En = spdif_En; SPDIF_ENC_RESET(current_Resolution > 16, SampleRate); } } } — Reply to this email directly, view it on GitHub <#2031 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAK6QRAK3QBQ3TZCKJ5YK3DXBUFZJANCNFSM6AAAAAAW7TIV5I> . You are receiving this because you authored the thread.Message ID: ***@***.***>