mirror/tinyusb
3
0
Fork 0
mirror of https://github.com/hathach/tinyusb.git synced 2026-03-29 19:03:34 +00:00
Code Issues Packages Projects Releases Wiki Activity

Implement RX FIFO threshold adjustment

Browse Source 
Signed-off-by: HiFiPhile <admin@hifiphile.com>
This commit is contained in:
HiFiPhile
2025-11-07 13:19:33 +01:00
parent 239ed48e22
commit 4fcce0fbc9
3 changed files with 28 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
examples/device/uac2_speaker_fb/src/main.c
View File

@ -35,13 +35,6 @@
// MACRO CONSTANT TYPEDEF PROTOTYPES
//--------------------------------------------------------------------+
// List of supported sample rates for UAC2
const uint32_t sample_rates[] = {44100, 48000, 88200, 96000};
#define N_SAMPLE_RATES TU_ARRAY_SIZE(sample_rates)
uint32_t current_sample_rate = 44100;
/* Blink pattern
* - 25 ms : streaming data
* - 250 ms : device not mounted
@ -76,6 +69,7 @@ static uint32_t blink_interval_ms = BLINK_NOT_MOUNTED;
// Current states
uint8_t mute[CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1]; // +1 for master channel 0
int16_t volume[CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1];// +1 for master channel 0
uint32_t current_sample_rate = 44100;
// Buffer for speaker data
uint16_t i2s_dummy_buffer[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ / 2];
@ -316,6 +310,10 @@ static bool audio10_get_req_entity(uint8_t rhport, tusb_control_request_t const
//--------------------------------------------------------------------+
#if TUD_OPT_HIGH_SPEED
// List of supported sample rates for UAC2
const uint32_t sample_rates[] = {44100, 48000, 88200, 96000};
#define N_SAMPLE_RATES TU_ARRAY_SIZE(sample_rates)
static bool audio20_clock_get_request(uint8_t rhport, audio20_control_request_t const *request) {
TU_ASSERT(request->bEntityID == UAC2_ENTITY_CLOCK);
@ -548,6 +546,17 @@ void tud_audio_feedback_params_cb(uint8_t func_id, uint8_t alt_itf, audio_feedba
// Set feedback method to fifo counting
feedback_param->method = AUDIO_FEEDBACK_METHOD_FIFO_COUNT;
feedback_param->sample_freq = current_sample_rate;
// About FIFO threshold:
//
// By default the threshold is set to half FIFO size, which works well in most cases,
// you can reduce the threshold to have less latency.
//
// For example, here we could set the threshold to 2 ms of audio data, as audio_task() read audio data every 1 ms,
// having 2 ms threshold allows some margin and a quick response:
//
// feedback_param->fifo_count.fifo_threshold =
// current_sample_rate * CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX * CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX / 1000 * 2;
}
#if CFG_AUDIO_DEBUG

14
src/class/audio/audio_device.c
View File

@ -1546,7 +1546,7 @@ static bool audiod_fb_params_prepare(uint8_t func_id, uint8_t alt) {
// Prepare feedback computation if endpoint is available
if (audio->ep_fb != 0) {
audio_feedback_params_t fb_param;
audio_feedback_params_t fb_param = {0};
tud_audio_feedback_params_cb(func_id, alt, &fb_param);
audio->feedback.compute_method = fb_param.method;
@ -1587,15 +1587,15 @@ static bool audiod_fb_params_prepare(uint8_t func_id, uint8_t alt) {
} break;
case AUDIO_FEEDBACK_METHOD_FIFO_COUNT: {
// Initialize the threshold level to half filled
uint16_t fifo_lvl_thr = tu_fifo_depth(&audio->ep_out_ff) / 2;
audio->feedback.compute.fifo_count.fifo_lvl_thr = fifo_lvl_thr;
audio->feedback.compute.fifo_count.fifo_lvl_avg = ((uint32_t) fifo_lvl_thr) << 16;
// Determine FIFO threshold
uint16_t fifo_threshold = fb_param.fifo_count.fifo_threshold ? fb_param.fifo_count.fifo_threshold : tu_fifo_depth(&audio->ep_out_ff) / 2;
audio->feedback.compute.fifo_count.fifo_lvl_thr = fifo_threshold;
audio->feedback.compute.fifo_count.fifo_lvl_avg = ((uint32_t) fifo_threshold) << 16;
// Avoid 64bit division
uint32_t nominal = ((fb_param.sample_freq / 100) << 16) / (frame_div / 100);
audio->feedback.compute.fifo_count.nom_value = nominal;
audio->feedback.compute.fifo_count.rate_const[0] = (uint16_t) ((audio->feedback.max_value - nominal) / fifo_lvl_thr);
audio->feedback.compute.fifo_count.rate_const[1] = (uint16_t) ((nominal - audio->feedback.min_value) / fifo_lvl_thr);
audio->feedback.compute.fifo_count.rate_const[0] = (uint16_t) ((audio->feedback.max_value - nominal) / fifo_threshold);
audio->feedback.compute.fifo_count.rate_const[1] = (uint16_t) ((nominal - audio->feedback.min_value) / fifo_threshold);
// On HS feedback is more sensitive since packet size can vary every MSOF, could cause instability
if (tud_speed_get() == TUSB_SPEED_HIGH) {
audio->feedback.compute.fifo_count.rate_const[0] /= 8;

8
src/class/audio/audio_device.h
View File

@ -333,10 +333,12 @@ typedef struct {
union {
struct {
uint32_t mclk_freq; // Main clock frequency in Hz i.e. master clock to which sample clock is based on
}frequency;
} frequency;
struct {
uint16_t fifo_threshold; // Target FIFO threshold level, default to half FIFO if not set
} fifo_count;
};
}audio_feedback_params_t;
} audio_feedback_params_t;
// Invoked when needed to set feedback parameters
void tud_audio_feedback_params_cb(uint8_t func_id, uint8_t alt_itf, audio_feedback_params_t* feedback_param);