initial commit

third_party/tinyusb/examples/device/uac2_speaker_fb/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.20)
+
+include(${CMAKE_CURRENT_SOURCE_DIR}/../../../hw/bsp/family_support.cmake)
+
+project(uac2_speaker_fb C CXX ASM)
+
+# Checks this example is valid for the family and initializes the project
+family_initialize_project(${PROJECT_NAME} ${CMAKE_CURRENT_LIST_DIR})
+
+# Espressif has its own cmake build system
+if(FAMILY STREQUAL "espressif")
+  return()
+endif()
+
+add_executable(${PROJECT_NAME})
+
+# Example source
+target_sources(${PROJECT_NAME} PUBLIC
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/main.c
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/usb_descriptors.c
+        )
+
+# Example include
+target_include_directories(${PROJECT_NAME} PUBLIC
+        ${CMAKE_CURRENT_SOURCE_DIR}/src
+        )
+
+# Configure compilation flags and libraries for the example without RTOS.
+# See the corresponding function in hw/bsp/FAMILY/family.cmake for details.
+family_configure_device_example(${PROJECT_NAME} noos)

third_party/tinyusb/examples/device/uac2_speaker_fb/CMakePresets.json

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+{
+  "version": 6,
+  "include": [
+    "../../../hw/bsp/BoardPresets.json"
+  ]
+}

third_party/tinyusb/examples/device/uac2_speaker_fb/Makefile

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+include ../../../hw/bsp/family_support.mk
+
+INC += \
+  src \
+
+
+# Example source
+EXAMPLE_SOURCE += $(wildcard src/*.c)
+SRC_C += $(addprefix $(EXAMPLE_PATH)/, $(EXAMPLE_SOURCE))
+
+include ../../../hw/bsp/family_rules.mk

third_party/tinyusb/examples/device/uac2_speaker_fb/README.md

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+# USB Speaker with Feedback
+
+A stereo USB speaker (output only) that uses an explicit isochronous feedback endpoint to keep the host's sample rate in sync, adapting its descriptors to the negotiated bus speed — UAC1 at Full-Speed and UAC2 at High-Speed.
+
+## What it does
+
+- Enumerates as a stereo speaker (host → device), 16-bit. The configuration returned depends on link speed: a UAC1 configuration at Full-Speed and a UAC2 configuration at High-Speed, with a device-qualifier and other-speed-configuration descriptor so it works at either speed.
+- Declares an explicit asynchronous feedback endpoint and reports rate via the FIFO-count feedback method (`tud_audio_feedback_params_cb`), letting the host adjust how many samples it sends so the device buffer neither under- nor over-runs.
+- The audio task drains the speaker FIFO every 1 ms into a dummy buffer (the data is discarded), reading roughly one millisecond of audio per cycle with a small periodic adjustment for the 44.1 kHz and 88.2 kHz rates.
+- Supports 44.1 kHz and 48 kHz at Full-Speed, plus 88.2 kHz and 96 kHz at High-Speed (UAC2). Handles UAC1 and UAC2 control requests (mute, volume, sample frequency).
+- When `CFG_AUDIO_DEBUG` is enabled (default), adds a HID interface that reports debug telemetry — current sample rate, alternate setting, mute/volume, and FIFO size/count/average — every 1 ms.
+- Blinks the on-board LED to indicate USB state, with a fast pattern while streaming.
+
+## USB Descriptors
+
+| Interface | Class driver |
+|-----------|--------------|
+| 0–1 | UAC2 audio (control + streaming), stereo speaker output with feedback endpoint |
+| 2 | HID (vendor report) — audio debug telemetry, present only when `CFG_AUDIO_DEBUG` is enabled |
+
+(UAC1 at Full-Speed, UAC2 at High-Speed.)
+
+## Configuration
+
+Notable `tusb_config.h` settings:
+
+```c
+#define CFG_TUD_AUDIO                                 1
+#define CFG_AUDIO_DEBUG                               1   // adds HID debug interface
+#define CFG_TUD_HID                                   1   // present when CFG_AUDIO_DEBUG
+#define CFG_TUD_AUDIO_ENABLE_EP_OUT                   1   // speaker
+#define CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP             1
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX            2   // stereo
+#define CFG_TUD_AUDIO_FUNC_1_RESOLUTION_RX            16  // 16-bit
+#define CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE_FS       48000
+#define CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE_HS       96000
+```
+
+## Building
+
+CMake:
+
+```bash
+mkdir build && cd build
+cmake -DBOARD=raspberry_pi_pico ..
+cmake --build .
+```
+
+Make:
+
+```bash
+make BOARD=raspberry_pi_pico all
+```
+
+## Try it
+
+The device appears as a stereo USB speaker; select it as the system output or play to it with `aplay`/`speaker-test` (the audio is consumed and discarded). The feedback endpoint keeps the host's send rate matched to the device. With `CFG_AUDIO_DEBUG` enabled, `src/audio_debug.py` reads the HID telemetry stream and plots the FIFO level and sample rate.

third_party/tinyusb/examples/device/uac2_speaker_fb/skip.txt

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+mcu:LPC11UXX
+mcu:LPC13XX
+mcu:NUC121
+mcu:SAMD11
+mcu:SAME5X
+mcu:SAMG
+board:stm32l052dap52
+family:broadcom_64bit
+mcu:CH583

third_party/tinyusb/examples/device/uac2_speaker_fb/src/audio_debug.py

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+#!/usr/bin/env python3
+# Install python3 HID package https://pypi.org/project/hid/
+# Install python3 matplotlib package https://pypi.org/project/matplotlib/
+
+from ctypes import Structure, c_uint32, c_uint8, c_int8, c_int16, c_uint16
+import signal
+try:
+    import hid
+    import matplotlib.pyplot as plt
+    import matplotlib.animation as animation
+except:
+    print("Missing import, please try 'pip install hid matplotlib' or consult your OS's python package manager.")
+    exit(1)
+
+# Example must be compiled with CFG_AUDIO_DEBUG=1
+VID = 0xcafe
+PID = 0x4014
+
+CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX = 2
+
+class audio_debug_info_t (Structure):
+    _fields_ = [("sample_rate", c_uint32),
+                ("alt_settings", c_uint8),
+                ("mute", (CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1) * c_int8),
+                ("volume", (CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1) * c_int16),
+                ("fifo_size", c_uint16),
+                ("fifo_count", c_uint16),
+                ("fifo_count_avg", c_uint16)
+                ]
+
+dev = hid.Device(VID, PID)
+
+if dev:
+    signal.signal(signal.SIGINT, signal.SIG_DFL)
+    # Create figure for plotting
+    fig = plt.figure()
+    ax = fig.add_subplot(1, 1, 1)
+    fifo_avg = []
+    fifo_cnt = []
+    # This function is called periodically from FuncAnimation
+    def animate(i):
+        info = None
+        for i in range(30):
+            try:
+                str_in = dev.read(64, 50)
+                info = audio_debug_info_t.from_buffer_copy(str_in)
+
+                global fifo_avg
+                global fifo_cnt
+                fifo_avg.append(info.fifo_count_avg)
+                fifo_cnt.append(info.fifo_count)
+            except:
+                exit(1)
+        # Limit to 1000 items
+        fifo_avg = fifo_avg[-1000:]
+        fifo_cnt = fifo_cnt[-1000:]
+
+        if info is not None:
+            # Draw x and y lists
+            ax.clear()
+            ax.plot(fifo_cnt, label='FIFO count')
+            ax.plot(fifo_avg, label='FIFO average')
+            ax.legend()
+            ax.set_ylim(bottom=0, top=info.fifo_size)
+
+            # Format plot
+            ax.set_title('FIFO information')
+            ax.grid(True)
+
+            print(f'Sample rate:{info.sample_rate} | Alt settings:{info.alt_settings} | Volume:{info.volume[:]}')
+
+    ani = animation.FuncAnimation(fig, animate, interval=10, cache_frame_data=False) # type: ignore
+    plt.show(block=True)

third_party/tinyusb/examples/device/uac2_speaker_fb/src/common_types.h

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+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2023 HiFiPhile
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#ifndef _COMMON_TYPES_H_
+#define _COMMON_TYPES_H_
+
+enum
+{
+  ITF_NUM_AUDIO_CONTROL = 0,
+  ITF_NUM_AUDIO_STREAMING,
+#if CFG_AUDIO_DEBUG
+  ITF_NUM_DEBUG,
+#endif
+  ITF_NUM_TOTAL
+};
+
+#if CFG_AUDIO_DEBUG
+typedef struct
+  {
+    uint32_t sample_rate;
+    uint8_t alt_settings;
+    uint8_t mute[CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1];
+    int16_t volume[CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1];
+    uint16_t fifo_size;
+    uint16_t fifo_count;
+    uint16_t fifo_count_avg;
+  } audio_debug_info_t;
+#endif
+
+#endif

third_party/tinyusb/examples/device/uac2_speaker_fb/src/main.c

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+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Jerzy Kasenberg
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "bsp/board_api.h"
+#include "common_types.h"
+#include "tusb.h"
+#include "usb_descriptors.h"
+
+//--------------------------------------------------------------------+
+// MACRO CONSTANT TYPEDEF PROTOTYPES
+//--------------------------------------------------------------------+
+
+/* Blink pattern
+ * - 25 ms   : streaming data
+ * - 250 ms  : device not mounted
+ * - 1000 ms : device mounted
+ * - 2500 ms : device is suspended
+ */
+enum {
+  BLINK_STREAMING = 25,
+  BLINK_NOT_MOUNTED = 250,
+  BLINK_MOUNTED = 1000,
+  BLINK_SUSPENDED = 2500,
+};
+
+enum {
+  VOLUME_CTRL_0_DB = 0,
+  VOLUME_CTRL_10_DB = 2560,
+  VOLUME_CTRL_20_DB = 5120,
+  VOLUME_CTRL_30_DB = 7680,
+  VOLUME_CTRL_40_DB = 10240,
+  VOLUME_CTRL_50_DB = 12800,
+  VOLUME_CTRL_60_DB = 15360,
+  VOLUME_CTRL_70_DB = 17920,
+  VOLUME_CTRL_80_DB = 20480,
+  VOLUME_CTRL_90_DB = 23040,
+  VOLUME_CTRL_100_DB = 25600,
+  VOLUME_CTRL_SILENCE = 0x8000,
+};
+
+static uint32_t blink_interval_ms = BLINK_NOT_MOUNTED;
+
+// Audio controls
+// 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];
+
+void led_blinking_task(void);
+void audio_task(void);
+
+#if CFG_AUDIO_DEBUG
+void audio_debug_task(void);
+uint8_t current_alt_settings;
+volatile uint16_t fifo_count;
+volatile uint32_t fifo_count_avg;
+#endif
+
+/*------------- MAIN -------------*/
+int main(void) {
+  board_init();
+
+  // init device stack on configured roothub port
+  tusb_rhport_init_t dev_init = {
+      .role = TUSB_ROLE_DEVICE,
+      .speed = TUSB_SPEED_AUTO};
+  tusb_init(BOARD_TUD_RHPORT, &dev_init);
+
+  board_init_after_tusb();
+
+  TU_LOG1("Speaker running\r\n");
+
+  while (1) {
+    tud_task();// TinyUSB device task
+    led_blinking_task();
+#if CFG_AUDIO_DEBUG
+    audio_debug_task();
+#endif
+    audio_task();
+  }
+}
+
+//--------------------------------------------------------------------+
+// Device callbacks
+//--------------------------------------------------------------------+
+
+// Invoked when device is mounted
+void tud_mount_cb(void) {
+  blink_interval_ms = BLINK_MOUNTED;
+}
+
+// Invoked when device is unmounted
+void tud_umount_cb(void) {
+  blink_interval_ms = BLINK_NOT_MOUNTED;
+}
+
+// Invoked when usb bus is suspended
+// remote_wakeup_en : if host allow us  to perform remote wakeup
+// Within 7ms, device must draw an average of current less than 2.5 mA from bus
+void tud_suspend_cb(bool remote_wakeup_en) {
+  (void) remote_wakeup_en;
+  blink_interval_ms = BLINK_SUSPENDED;
+}
+
+// Invoked when usb bus is resumed
+void tud_resume_cb(void) {
+  blink_interval_ms = tud_mounted() ? BLINK_MOUNTED : BLINK_NOT_MOUNTED;
+}
+
+//--------------------------------------------------------------------+
+// Application Callback API Implementations
+//--------------------------------------------------------------------+
+
+//--------------------------------------------------------------------+
+// UAC1 Helper Functions
+//--------------------------------------------------------------------+
+
+static bool audio10_set_req_ep(tusb_control_request_t const *p_request, uint8_t *pBuff) {
+  uint8_t ctrlSel = TU_U16_HIGH(p_request->wValue);
+
+  switch (ctrlSel) {
+    case AUDIO10_EP_CTRL_SAMPLING_FREQ:
+      if (p_request->bRequest == AUDIO10_CS_REQ_SET_CUR) {
+        // Request uses 3 bytes
+        TU_VERIFY(p_request->wLength == 3);
+
+        current_sample_rate = tu_unaligned_read32(pBuff) & 0x00FFFFFF;
+
+        TU_LOG2("EP set current freq: %" PRIu32 "\r\n", current_sample_rate);
+
+        return true;
+      }
+      break;
+
+    // Unknown/Unsupported control
+    default:
+      TU_BREAKPOINT();
+      return false;
+  }
+
+  return false;
+}
+
+static bool audio10_get_req_ep(uint8_t rhport, tusb_control_request_t const *p_request) {
+  uint8_t ctrlSel = TU_U16_HIGH(p_request->wValue);
+
+  switch (ctrlSel) {
+    case AUDIO10_EP_CTRL_SAMPLING_FREQ:
+      if (p_request->bRequest == AUDIO10_CS_REQ_GET_CUR) {
+        TU_LOG2("EP get current freq\r\n");
+
+        uint8_t freq[3];
+        freq[0] = (uint8_t) (current_sample_rate & 0xFF);
+        freq[1] = (uint8_t) ((current_sample_rate >> 8) & 0xFF);
+        freq[2] = (uint8_t) ((current_sample_rate >> 16) & 0xFF);
+        return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, freq, sizeof(freq));
+      }
+      break;
+
+    // Unknown/Unsupported control
+    default:
+      TU_BREAKPOINT();
+      return false;
+  }
+
+  return false;
+}
+
+static bool audio10_set_req_entity(tusb_control_request_t const *p_request, uint8_t *pBuff) {
+  uint8_t channelNum = TU_U16_LOW(p_request->wValue);
+  uint8_t ctrlSel = TU_U16_HIGH(p_request->wValue);
+  uint8_t entityID = TU_U16_HIGH(p_request->wIndex);
+
+  // If request is for our feature unit
+  if (entityID == UAC1_ENTITY_FEATURE_UNIT) {
+    switch (ctrlSel) {
+      case AUDIO10_FU_CTRL_MUTE:
+        switch (p_request->bRequest) {
+          case AUDIO10_CS_REQ_SET_CUR:
+            // Only 1st form is supported
+            TU_VERIFY(p_request->wLength == 1);
+
+            mute[channelNum] = pBuff[0];
+
+            TU_LOG2("    Set Mute: %d of channel: %u\r\n", mute[channelNum], channelNum);
+            return true;
+
+          default:
+            return false; // not supported
+        }
+
+      case AUDIO10_FU_CTRL_VOLUME:
+        switch (p_request->bRequest) {
+          case AUDIO10_CS_REQ_SET_CUR:
+            // Only 1st form is supported
+            TU_VERIFY(p_request->wLength == 2);
+
+            volume[channelNum] = (int16_t)tu_unaligned_read16(pBuff) / 256;
+
+            TU_LOG2("    Set Volume: %d dB of channel: %u\r\n", volume[channelNum], channelNum);
+            return true;
+
+          default:
+            return false; // not supported
+        }
+
+        // Unknown/Unsupported control
+      default:
+        TU_BREAKPOINT();
+        return false;
+    }
+  }
+
+  return false;
+}
+
+static bool audio10_get_req_entity(uint8_t rhport, tusb_control_request_t const *p_request) {
+  uint8_t channelNum = TU_U16_LOW(p_request->wValue);
+  uint8_t ctrlSel = TU_U16_HIGH(p_request->wValue);
+  uint8_t entityID = TU_U16_HIGH(p_request->wIndex);
+
+  // If request is for our feature unit
+  if (entityID == UAC1_ENTITY_FEATURE_UNIT) {
+    switch (ctrlSel) {
+      case AUDIO10_FU_CTRL_MUTE:
+        // Audio control mute cur parameter block consists of only one byte - we thus can send it right away
+        // There does not exist a range parameter block for mute
+        TU_LOG2("    Get Mute of channel: %u\r\n", channelNum);
+        return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &mute[channelNum], 1);
+
+      case AUDIO10_FU_CTRL_VOLUME:
+        switch (p_request->bRequest) {
+          case AUDIO10_CS_REQ_GET_CUR:
+            TU_LOG2("    Get Volume of channel: %u\r\n", channelNum);
+            {
+              int16_t vol = (int16_t) volume[channelNum];
+              vol = vol * 256; // convert to 1/256 dB units
+              return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &vol, sizeof(vol));
+            }
+
+          case AUDIO10_CS_REQ_GET_MIN:
+            TU_LOG2("    Get Volume min of channel: %u\r\n", channelNum);
+            {
+              int16_t min = -90; // -90 dB
+              min = min * 256; // convert to 1/256 dB units
+              return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &min, sizeof(min));
+            }
+
+          case AUDIO10_CS_REQ_GET_MAX:
+            TU_LOG2("    Get Volume max of channel: %u\r\n", channelNum);
+            {
+              int16_t max = 30; // +30 dB
+              max = max * 256; // convert to 1/256 dB units
+              return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &max, sizeof(max));
+            }
+
+          case AUDIO10_CS_REQ_GET_RES:
+            TU_LOG2("    Get Volume res of channel: %u\r\n", channelNum);
+            {
+              int16_t res = 128; // 0.5 dB
+              return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &res, sizeof(res));
+            }
+            // Unknown/Unsupported control
+          default:
+            TU_BREAKPOINT();
+            return false;
+        }
+        break;
+
+        // Unknown/Unsupported control
+      default:
+        TU_BREAKPOINT();
+        return false;
+    }
+  }
+
+  return false;
+}
+
+//--------------------------------------------------------------------+
+// UAC2 Helper Functions
+//--------------------------------------------------------------------+
+
+#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, tusb_control_request_t const *p_request) {
+  uint8_t const ctrl_sel = TU_U16_HIGH(p_request->wValue);
+
+  if (ctrl_sel == AUDIO20_CS_CTRL_SAM_FREQ) {
+    if (p_request->bRequest == AUDIO20_CS_REQ_CUR) {
+      TU_LOG1("Clock get current freq %" PRIu32 "\r\n", current_sample_rate);
+
+      audio20_control_cur_4_t curf = {(int32_t) tu_htole32(current_sample_rate)};
+      return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &curf, sizeof(curf));
+    } else if (p_request->bRequest == AUDIO20_CS_REQ_RANGE) {
+      audio20_control_range_4_n_t(N_SAMPLE_RATES) rangef =
+          {
+              .wNumSubRanges = tu_htole16(N_SAMPLE_RATES)};
+      TU_LOG1("Clock get %d freq ranges\r\n", N_SAMPLE_RATES);
+      for (uint8_t i = 0; i < N_SAMPLE_RATES; i++) {
+        rangef.subrange[i].bMin = (int32_t) sample_rates[i];
+        rangef.subrange[i].bMax = (int32_t) sample_rates[i];
+        rangef.subrange[i].bRes = 0;
+        TU_LOG1("Range %d (%d, %d, %d)\r\n", i, (int) rangef.subrange[i].bMin, (int) rangef.subrange[i].bMax, (int) rangef.subrange[i].bRes);
+      }
+
+      return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &rangef, sizeof(rangef));
+    }
+  } else if (ctrl_sel == AUDIO20_CS_CTRL_CLK_VALID &&
+             p_request->bRequest == AUDIO20_CS_REQ_CUR) {
+    audio20_control_cur_1_t cur_valid = {.bCur = 1};
+    TU_LOG1("Clock get is valid %u\r\n", cur_valid.bCur);
+    return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &cur_valid, sizeof(cur_valid));
+  }
+  TU_LOG1("Clock get request not supported, selector = %u, request = %u\r\n",
+          ctrl_sel, p_request->bRequest);
+  return false;
+}
+
+static bool audio20_clock_set_request(tusb_control_request_t const *p_request, uint8_t const *buf) {
+  uint8_t const ctrl_sel = TU_U16_HIGH(p_request->wValue);
+
+  TU_VERIFY(p_request->bRequest == AUDIO20_CS_REQ_CUR);
+
+  if (ctrl_sel == AUDIO20_CS_CTRL_SAM_FREQ) {
+    TU_VERIFY(p_request->wLength == sizeof(audio20_control_cur_4_t));
+
+    current_sample_rate = (uint32_t) ((audio20_control_cur_4_t const *) buf)->bCur;
+
+    TU_LOG1("Clock set current freq: %" PRIu32 "\r\n", current_sample_rate);
+
+    return true;
+  } else {
+    TU_LOG1("Clock set request not supported, selector = %u, request = %u\r\n",
+            ctrl_sel, p_request->bRequest);
+    return false;
+  }
+}
+
+static bool audio20_feature_unit_get_request(uint8_t rhport, tusb_control_request_t const *p_request) {
+  uint8_t const ctrl_sel    = TU_U16_HIGH(p_request->wValue);
+  uint8_t const channel_num = TU_U16_LOW(p_request->wValue);
+
+  if (ctrl_sel == AUDIO20_FU_CTRL_MUTE && p_request->bRequest == AUDIO20_CS_REQ_CUR) {
+    audio20_control_cur_1_t mute1 = {.bCur = mute[channel_num]};
+    TU_LOG1("Get channel %u mute %d\r\n", channel_num, mute1.bCur);
+    return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &mute1, sizeof(mute1));
+  } else if (ctrl_sel == AUDIO20_FU_CTRL_VOLUME) {
+    if (p_request->bRequest == AUDIO20_CS_REQ_RANGE) {
+      audio20_control_range_2_n_t(1) range_vol = {
+          .wNumSubRanges = tu_htole16(1),
+          .subrange[0] = {.bMin = tu_htole16(-VOLUME_CTRL_50_DB), tu_htole16(VOLUME_CTRL_0_DB), tu_htole16(256)}};
+      TU_LOG1("Get channel %u volume range (%d, %d, %u) dB\r\n", channel_num,
+              range_vol.subrange[0].bMin / 256, range_vol.subrange[0].bMax / 256, range_vol.subrange[0].bRes / 256);
+      return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &range_vol, sizeof(range_vol));
+    } else if (p_request->bRequest == AUDIO20_CS_REQ_CUR) {
+      audio20_control_cur_2_t cur_vol = {.bCur = tu_htole16(volume[channel_num])};
+      TU_LOG1("Get channel %u volume %d dB\r\n", channel_num, cur_vol.bCur / 256);
+      return tud_audio_buffer_and_schedule_control_xfer(rhport, p_request, &cur_vol, sizeof(cur_vol));
+    }
+  }
+  TU_LOG1("Feature unit get request not supported, selector = %u, request = %u\r\n",
+          ctrl_sel, p_request->bRequest);
+
+  return false;
+}
+
+static bool audio20_feature_unit_set_request(tusb_control_request_t const *p_request, uint8_t const *buf) {
+  uint8_t const ctrl_sel    = TU_U16_HIGH(p_request->wValue);
+  uint8_t const channel_num = TU_U16_LOW(p_request->wValue);
+
+  TU_VERIFY(p_request->bRequest == AUDIO20_CS_REQ_CUR);
+
+  if (ctrl_sel == AUDIO20_FU_CTRL_MUTE) {
+    TU_VERIFY(p_request->wLength == sizeof(audio20_control_cur_1_t));
+
+    mute[channel_num] = ((audio20_control_cur_1_t const *) buf)->bCur;
+
+    TU_LOG1("Set channel %d Mute: %d\r\n", channel_num, mute[channel_num]);
+
+    return true;
+  } else if (ctrl_sel == AUDIO20_FU_CTRL_VOLUME) {
+    TU_VERIFY(p_request->wLength == sizeof(audio20_control_cur_2_t));
+
+    volume[channel_num] = ((audio20_control_cur_2_t const *) buf)->bCur;
+
+    TU_LOG1("Set channel %d volume: %d dB\r\n", channel_num, volume[channel_num] / 256);
+
+    return true;
+  } else {
+    TU_LOG1("Feature unit set request not supported, selector = %u, request = %u\r\n",
+            ctrl_sel, p_request->bRequest);
+    return false;
+  }
+}
+
+static bool audio20_get_req_entity(uint8_t rhport, tusb_control_request_t const *p_request) {
+  uint8_t const entity_id = TU_U16_HIGH(p_request->wIndex);
+
+  if (entity_id == UAC2_ENTITY_CLOCK)
+    return audio20_clock_get_request(rhport, p_request);
+  if (entity_id == UAC2_ENTITY_FEATURE_UNIT)
+    return audio20_feature_unit_get_request(rhport, p_request);
+  else {
+    TU_LOG1("Get request not handled, entity = %d, selector = %d, request = %d\r\n",
+            entity_id, TU_U16_HIGH(p_request->wValue), p_request->bRequest);
+  }
+  return false;
+}
+
+static bool audio20_set_req_entity(tusb_control_request_t const *p_request, uint8_t *buf) {
+  uint8_t const entity_id = TU_U16_HIGH(p_request->wIndex);
+
+  if (entity_id == UAC2_ENTITY_FEATURE_UNIT)
+    return audio20_feature_unit_set_request(p_request, buf);
+  if (entity_id == UAC2_ENTITY_CLOCK)
+    return audio20_clock_set_request(p_request, buf);
+  TU_LOG1("Set request not handled, entity = %d, selector = %d, request = %d\r\n",
+          entity_id, TU_U16_HIGH(p_request->wValue), p_request->bRequest);
+
+  return false;
+}
+
+#endif // TUD_OPT_HIGH_SPEED
+
+//--------------------------------------------------------------------+
+// Main Callback Functions
+//--------------------------------------------------------------------+
+
+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(p_request->wIndex);
+  uint8_t const alt = tu_u16_low(p_request->wValue);
+
+  TU_LOG2("Set interface %d alt %d\r\n", itf, alt);
+  if (ITF_NUM_AUDIO_STREAMING == itf && alt != 0)
+    blink_interval_ms = BLINK_STREAMING;
+
+#if CFG_AUDIO_DEBUG
+  current_alt_settings = alt;
+#endif
+
+  return true;
+}
+
+// Invoked when audio class specific set request received for an EP
+bool tud_audio_set_req_ep_cb(uint8_t rhport, tusb_control_request_t const *p_request, uint8_t *pBuff) {
+  (void) rhport;
+  (void) pBuff;
+
+  if (tud_audio_version() == 1) {
+    return audio10_set_req_ep(p_request, pBuff);
+  } else if (tud_audio_version() == 2) {
+    // We do not support any requests here
+  }
+
+  return false;// Yet not implemented
+}
+
+// Invoked when audio class specific get request received for an EP
+bool tud_audio_get_req_ep_cb(uint8_t rhport, tusb_control_request_t const *p_request) {
+  (void) rhport;
+
+  if (tud_audio_version() == 1) {
+    return audio10_get_req_ep(rhport, p_request);
+  } else if (tud_audio_version() == 2) {
+    // We do not support any requests here
+  }
+
+  return false;// Yet not implemented
+}
+
+// Invoked when audio class specific set request received for an entity
+bool tud_audio_set_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p_request, uint8_t *buf) {
+  (void) rhport;
+
+  if (tud_audio_version() == 1) {
+    return audio10_set_req_entity(p_request, buf);
+#if TUD_OPT_HIGH_SPEED
+  } else if (tud_audio_version() == 2) {
+    return audio20_set_req_entity(p_request, buf);
+#endif
+  }
+
+  return false;
+}
+
+// Invoked when audio class specific get request received for an entity
+bool tud_audio_get_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p_request) {
+  (void) rhport;
+
+  if (tud_audio_version() == 1) {
+    return audio10_get_req_entity(rhport, p_request);
+#if TUD_OPT_HIGH_SPEED
+  } else if (tud_audio_version() == 2) {
+    return audio20_get_req_entity(rhport, p_request);
+#endif
+  }
+
+  return false;
+}
+
+bool tud_audio_set_itf_close_ep_cb(uint8_t rhport, tusb_control_request_t const *p_request) {
+  (void) rhport;
+
+  uint8_t const itf = tu_u16_low(p_request->wIndex);
+  uint8_t const alt = tu_u16_low(p_request->wValue);
+
+  if (ITF_NUM_AUDIO_STREAMING == itf && alt == 0) {
+    blink_interval_ms = BLINK_MOUNTED;
+  }
+
+  return true;
+}
+
+void tud_audio_feedback_params_cb(uint8_t func_id, uint8_t alt_itf, audio_feedback_params_t *feedback_param) {
+  (void) func_id;
+  (void) alt_itf;
+  // 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
+bool tud_audio_rx_done_isr(uint8_t rhport, uint16_t n_bytes_received, uint8_t func_id, uint8_t ep_out, uint8_t cur_alt_setting) {
+  (void) rhport;
+  (void) n_bytes_received;
+  (void) func_id;
+  (void) ep_out;
+  (void) cur_alt_setting;
+
+  fifo_count = tud_audio_available();
+  // Same averaging method used in UAC2 class
+  const uint32_t ff_count32 = (uint32_t) fifo_count << 16;
+  fifo_count_avg = (uint32_t) (((uint64_t) fifo_count_avg * 63 + ff_count32) >> 6);
+
+  return true;
+}
+#endif
+
+//--------------------------------------------------------------------+
+// AUDIO Task
+//--------------------------------------------------------------------+
+
+// This task simulates an audio transmit callback, one frame is sent every 1ms.
+// In a real application, this would be replaced with actual I2S transmit callback.
+void audio_task(void) {
+  static uint32_t start_ms = 0;
+  uint32_t curr_ms = tusb_time_millis_api();
+  if (start_ms == curr_ms) return;// not enough time
+  start_ms = curr_ms;
+
+  uint16_t length = (uint16_t) (current_sample_rate / 1000 * CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX);
+
+  if (current_sample_rate == 44100 && (curr_ms % 10 == 0)) {
+    // Take one more sample every 10 cycles, to have a average reading speed of 44.1
+    // This correction is not needed in real world cases
+    length += CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX;
+  } else if (current_sample_rate == 88200 && (curr_ms % 5 == 0)) {
+    // Take one more sample every 5 cycles, to have a average reading speed of 88.2
+    // This correction is not needed in real world cases
+    length += CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX * CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX;
+  }
+
+  tud_audio_read(i2s_dummy_buffer, length);
+}
+
+//--------------------------------------------------------------------+
+// BLINKING TASK
+//--------------------------------------------------------------------+
+void led_blinking_task(void) {
+  static uint32_t start_ms = 0;
+  static bool led_state = false;
+
+  // Blink every interval ms
+  if (tusb_time_millis_api() - start_ms < blink_interval_ms) return;
+  start_ms += blink_interval_ms;
+
+  board_led_write(led_state);
+  led_state = 1 - led_state;
+}
+
+#if CFG_AUDIO_DEBUG
+//--------------------------------------------------------------------+
+// HID interface for audio debug
+//--------------------------------------------------------------------+
+// Every 1ms, we will sent 1 debug information report
+void audio_debug_task(void) {
+  static uint32_t start_ms = 0;
+  uint32_t curr_ms = tusb_time_millis_api();
+  if (start_ms == curr_ms) return;// not enough time
+  start_ms = curr_ms;
+
+  audio_debug_info_t debug_info;
+  debug_info.sample_rate = current_sample_rate;
+  debug_info.alt_settings = current_alt_settings;
+  debug_info.fifo_size = CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ;
+  debug_info.fifo_count = fifo_count;
+  debug_info.fifo_count_avg = (uint16_t) (fifo_count_avg >> 16);
+  for (int i = 0; i < CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1; i++) {
+    debug_info.mute[i] = mute[i];
+    debug_info.volume[i] = volume[i];
+  }
+
+  if (tud_hid_ready())
+    tud_hid_report(0, &debug_info, sizeof(debug_info));
+}
+
+// Invoked when received GET_REPORT control request
+// Unused here
+uint16_t tud_hid_get_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t report_type, uint8_t *buffer, uint16_t reqlen) {
+  // TODO not Implemented
+  (void) itf;
+  (void) report_id;
+  (void) report_type;
+  (void) buffer;
+  (void) reqlen;
+
+  return 0;
+}
+
+// Invoked when received SET_REPORT control request or
+// Unused here
+void tud_hid_set_report_cb(uint8_t itf, uint8_t report_id, hid_report_type_t report_type, uint8_t const *buffer, uint16_t bufsize) {
+  // This example doesn't use multiple report and report ID
+  (void) itf;
+  (void) report_id;
+  (void) report_type;
+  (void) buffer;
+  (void) bufsize;
+}
+
+#endif

third_party/tinyusb/examples/device/uac2_speaker_fb/src/tusb_config.h

@@ -0,0 +1,152 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Ha Thach (tinyusb.org)
+ * Copyright (c) 2020 Jerzy Kasenberg
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#ifndef TUSB_CONFIG_H_
+#define TUSB_CONFIG_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "usb_descriptors.h"
+
+//--------------------------------------------------------------------+
+// Board Specific Configuration
+//--------------------------------------------------------------------+
+
+// RHPort number used for device can be defined by board.mk, default to port 0
+#ifndef BOARD_TUD_RHPORT
+#define BOARD_TUD_RHPORT      0
+#endif
+
+// RHPort max operational speed can defined by board.mk
+#ifndef BOARD_TUD_MAX_SPEED
+#define BOARD_TUD_MAX_SPEED   OPT_MODE_DEFAULT_SPEED
+#endif
+
+//--------------------------------------------------------------------
+// Common Configuration
+//--------------------------------------------------------------------
+
+// defined by compiler flags for flexibility
+#ifndef CFG_TUSB_MCU
+#error CFG_TUSB_MCU must be defined
+#endif
+
+#ifndef CFG_TUSB_OS
+#define CFG_TUSB_OS           OPT_OS_NONE
+#endif
+
+// It's recommended to disable debug unless for control requests debugging,
+// as the extra time needed will impact data stream !
+#ifndef CFG_TUSB_DEBUG
+#define CFG_TUSB_DEBUG        0
+#endif
+
+// Enable Device stack
+#define CFG_TUD_ENABLED       1
+
+// Default is max speed that hardware controller could support with on-chip PHY
+#define CFG_TUD_MAX_SPEED     BOARD_TUD_MAX_SPEED
+
+/* USB DMA on some MCUs can only access a specific SRAM region with restriction on alignment.
+ * Tinyusb use follows macros to declare transferring memory so that they can be put
+ * into those specific section.
+ * e.g
+ * - CFG_TUSB_MEM SECTION : __attribute__ (( section(".usb_ram") ))
+ * - CFG_TUSB_MEM_ALIGN   : __attribute__ ((aligned(4)))
+ */
+#ifndef CFG_TUSB_MEM_SECTION
+#define CFG_TUSB_MEM_SECTION
+#endif
+
+#ifndef CFG_TUSB_MEM_ALIGN
+#define CFG_TUSB_MEM_ALIGN        __attribute__ ((aligned(4)))
+#endif
+
+//--------------------------------------------------------------------
+// DEVICE CONFIGURATION
+//--------------------------------------------------------------------
+
+// Expose audio class debug information via HID interface
+#ifndef CFG_AUDIO_DEBUG
+#define CFG_AUDIO_DEBUG           1
+#endif
+
+#ifndef CFG_TUD_ENDPOINT0_SIZE
+#define CFG_TUD_ENDPOINT0_SIZE    64
+#endif
+
+#define CFG_TUD_HID_EP_BUFSIZE    64
+
+//------------- CLASS -------------//
+#define CFG_TUD_AUDIO             1
+
+#if CFG_AUDIO_DEBUG
+#define CFG_TUD_HID               1
+#else
+#define CFG_TUD_HID               0
+#endif
+
+#define CFG_TUD_CDC               0
+#define CFG_TUD_MSC               0
+#define CFG_TUD_MIDI              0
+#define CFG_TUD_VENDOR            0
+
+//--------------------------------------------------------------------
+// AUDIO CLASS DRIVER CONFIGURATION
+//--------------------------------------------------------------------
+
+#define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX              2
+
+// 16bit data in 16bit slots
+#define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX      2
+#define CFG_TUD_AUDIO_FUNC_1_RESOLUTION_RX              16
+
+// UAC1 Full-Speed endpoint size
+#define CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE_FS     48000
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_FS           TUD_AUDIO_EP_SIZE(false, CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE_FS, CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX)
+// UAC2 High-Speed endpoint size
+#define CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE_HS     96000
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_HS           TUD_AUDIO_EP_SIZE(true, CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE_HS, CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX)
+
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX          TU_MAX(CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_FS, CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_HS)
+
+// AUDIO_FEEDBACK_METHOD_FIFO_COUNT needs buffer size >= 4* EP size to work correctly
+// Example read FIFO every 1ms (8 HS frames), so buffer size should be 8 times larger for HS device
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ       TU_MAX(4 * CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_FS, 32 * CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_HS)
+
+// Enable OUT EP
+#define CFG_TUD_AUDIO_ENABLE_EP_OUT                 1
+
+// Enable feedback EP
+#define CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP            1
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* TUSB_CONFIG_H_ */

third_party/tinyusb/examples/device/uac2_speaker_fb/src/usb_descriptors.c

@@ -0,0 +1,299 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2023 HiFiPhile
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#include "bsp/board_api.h"
+#include "tusb.h"
+#include "usb_descriptors.h"
+#include "common_types.h"
+
+/* A combination of interfaces must have a unique product id, since PC will save device driver after the first plug.
+ * Same VID/PID with different interface e.g MSC (first), then CDC (later) will possibly cause system error on PC.
+ *
+ * Auto ProductID layout's Bitmap:
+ *   [MSB]     AUDIO | MIDI | HID | MSC | CDC          [LSB]
+ */
+#define PID_MAP(itf, n)  ((CFG_TUD_##itf) ? (1 << (n)) : 0)
+#define USB_PID           (0x4000 | PID_MAP(CDC, 0) | PID_MAP(MSC, 1) | PID_MAP(HID, 2) | \
+    PID_MAP(MIDI, 3) | PID_MAP(AUDIO, 4) | PID_MAP(VENDOR, 5) )
+
+//--------------------------------------------------------------------+
+// Device Descriptors
+//--------------------------------------------------------------------+
+static tusb_desc_device_t const desc_device =
+{
+    .bLength            = sizeof(tusb_desc_device_t),
+    .bDescriptorType    = TUSB_DESC_DEVICE,
+    .bcdUSB             = 0x0200,
+
+    // Use Interface Association Descriptor (IAD) for Audio
+    // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)
+    .bDeviceClass       = TUSB_CLASS_MISC,
+    .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
+    .bDeviceProtocol    = MISC_PROTOCOL_IAD,
+    .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,
+
+    .idVendor           = 0xCafe,
+    .idProduct          = USB_PID,
+    .bcdDevice          = 0x0100,
+
+    .iManufacturer      = 0x01,
+    .iProduct           = 0x02,
+    .iSerialNumber      = 0x03,
+
+    .bNumConfigurations = 0x01
+};
+
+// Invoked when received GET DEVICE DESCRIPTOR
+// Application return pointer to descriptor
+uint8_t const * tud_descriptor_device_cb(void) {
+  return (uint8_t const *) &desc_device;
+}
+
+#if CFG_AUDIO_DEBUG
+//--------------------------------------------------------------------+
+// HID Report Descriptor
+//--------------------------------------------------------------------+
+
+uint8_t const desc_hid_report[] = {
+  HID_USAGE_PAGE_N ( HID_USAGE_PAGE_VENDOR, 2   ),\
+  HID_USAGE        ( 0x01                       ),\
+  HID_COLLECTION   ( HID_COLLECTION_APPLICATION ),\
+  HID_USAGE       ( 0x02                                   ),\
+  HID_LOGICAL_MIN ( 0x00                                   ),\
+  HID_LOGICAL_MAX_N ( 0xff, 2                              ),\
+  HID_REPORT_SIZE ( 8                                      ),\
+  HID_REPORT_COUNT( sizeof(audio_debug_info_t)             ),\
+  HID_INPUT       ( HID_DATA | HID_VARIABLE | HID_ABSOLUTE ),\
+  HID_COLLECTION_END
+};
+
+// Invoked when received GET HID REPORT DESCRIPTOR
+// Application return pointer to descriptor
+// Descriptor contents must exist long enough for transfer to complete
+uint8_t const * tud_hid_descriptor_report_cb(uint8_t itf) {
+  (void) itf;
+  return desc_hid_report;
+}
+#endif
+
+//--------------------------------------------------------------------+
+// Configuration Descriptor
+//--------------------------------------------------------------------+
+
+#if CFG_TUSB_MCU == OPT_MCU_LPC175X_6X || CFG_TUSB_MCU == OPT_MCU_LPC177X_8X || CFG_TUSB_MCU == OPT_MCU_LPC40XX
+  // LPC 17xx and 40xx endpoint type (bulk/interrupt/iso) are fixed by its number
+  // 0 control, 1 In, 2 Bulk, 3 Iso, 4 In etc ...
+  #define EPNUM_AUDIO       0x03
+  #define EPNUM_AUDIO_FB    0x03
+  #define EPNUM_DEBUG       0x04
+
+#elif TU_CHECK_MCU(OPT_MCU_NRF5X)
+  // nRF5x ISO can only be endpoint 8
+  #define EPNUM_AUDIO       0x08
+  #define EPNUM_AUDIO_FB    0x08
+  #define EPNUM_DEBUG       0x01
+
+#elif CFG_TUD_ENDPOINT_ONE_DIRECTION_ONLY
+  // MCUs that don't support a same endpoint number with different direction IN and OUT defined in tusb_mcu.h
+  //    e.g EP1 OUT & EP1 IN cannot exist together
+  #if TU_CHECK_MCU(OPT_MCU_MAX32650, OPT_MCU_MAX32666, OPT_MCU_MAX32690, OPT_MCU_MAX78002)
+    // Put audio iso on EP10/11 so the 4096-byte FIFOs can back double packet buffering
+    #define EPNUM_AUDIO       0x0A
+    #define EPNUM_AUDIO_FB    0x0B
+    #define EPNUM_DEBUG       0x01
+  #else
+    #define EPNUM_AUDIO       0x02
+    #define EPNUM_AUDIO_FB    0x01
+    #define EPNUM_DEBUG       0x03
+  #endif
+
+#else
+  #define EPNUM_AUDIO       0x01
+  #define EPNUM_AUDIO_FB    0x01
+  #define EPNUM_DEBUG       0x02
+#endif
+
+#if CFG_AUDIO_DEBUG
+  #define CONFIG_UAC1_TOTAL_LEN    	(TUD_CONFIG_DESC_LEN + TUD_AUDIO10_SPEAKER_STEREO_FB_DESC_LEN(2) + TUD_HID_DESC_LEN)
+#else
+  #define CONFIG_UAC1_TOTAL_LEN    	(TUD_CONFIG_DESC_LEN + TUD_AUDIO10_SPEAKER_STEREO_FB_DESC_LEN(2))
+#endif
+
+uint8_t const desc_uac1_configuration[] = {
+  // Config number, interface count, string index, total length, attribute, power in mA
+  TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_UAC1_TOTAL_LEN, 0x00, 100),
+
+  // Interface number, string index, byte per sample, bit per sample, EP Out, EP size, EP feedback, sample rates (44.1kHz, 48kHz)
+  TUD_AUDIO10_SPEAKER_STEREO_FB_DESCRIPTOR(ITF_NUM_AUDIO_CONTROL, 5, CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_RESOLUTION_RX, EPNUM_AUDIO, CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_FS, EPNUM_AUDIO_FB | 0x80, 44100, 48000),
+
+#if CFG_AUDIO_DEBUG
+  // Interface number, string index, protocol, report descriptor len, EP In address, size & polling interval
+  TUD_HID_DESCRIPTOR(ITF_NUM_DEBUG, 0, HID_ITF_PROTOCOL_NONE, sizeof(desc_hid_report), EPNUM_DEBUG | 0x80, CFG_TUD_HID_EP_BUFSIZE, 7)
+#endif
+};
+
+TU_VERIFY_STATIC(sizeof(desc_uac1_configuration) == CONFIG_UAC1_TOTAL_LEN, "Incorrect size");
+
+#if TUD_OPT_HIGH_SPEED
+
+#if CFG_AUDIO_DEBUG
+  #define CONFIG_UAC2_TOTAL_LEN    	(TUD_CONFIG_DESC_LEN + TUD_AUDIO20_SPEAKER_STEREO_FB_DESC_LEN + TUD_HID_DESC_LEN)
+#else
+  #define CONFIG_UAC2_TOTAL_LEN    	(TUD_CONFIG_DESC_LEN + TUD_AUDIO20_SPEAKER_STEREO_FB_DESC_LEN)
+#endif
+
+uint8_t const desc_uac2_configuration[] = {
+  // Config number, interface count, string index, total length, attribute, power in mA
+  TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_UAC2_TOTAL_LEN, 0x00, 100),
+
+  // Interface number, string index, byte per sample, bit per sample, EP Out, EP size, EP feedback, feedback EP size,
+  TUD_AUDIO20_SPEAKER_STEREO_FB_DESCRIPTOR(ITF_NUM_AUDIO_CONTROL, 4, CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_RESOLUTION_RX, EPNUM_AUDIO, CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_HS, EPNUM_AUDIO_FB | 0x80, 4),
+
+#if CFG_AUDIO_DEBUG
+  // Interface number, string index, protocol, report descriptor len, EP In address, size & polling interval
+  TUD_HID_DESCRIPTOR(ITF_NUM_DEBUG, 0, HID_ITF_PROTOCOL_NONE, sizeof(desc_hid_report), EPNUM_DEBUG | 0x80, CFG_TUD_HID_EP_BUFSIZE, 7)
+#endif
+};
+
+TU_VERIFY_STATIC(sizeof(desc_uac2_configuration) == CONFIG_UAC2_TOTAL_LEN, "Incorrect size");
+
+// device qualifier is mostly similar to device descriptor since we don't change configuration based on speed
+tusb_desc_device_qualifier_t const desc_device_qualifier = {
+  .bLength            = sizeof(tusb_desc_device_qualifier_t),
+  .bDescriptorType    = TUSB_DESC_DEVICE_QUALIFIER,
+  .bcdUSB             = 0x0200,
+
+  .bDeviceClass       = TUSB_CLASS_MISC,
+  .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
+  .bDeviceProtocol    = MISC_PROTOCOL_IAD,
+
+  .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,
+  .bNumConfigurations = 0x01,
+  .bReserved          = 0x00
+};
+
+// Invoked when received GET DEVICE QUALIFIER DESCRIPTOR request
+// Application return pointer to descriptor, whose contents must exist long enough for transfer to complete.
+// device_qualifier descriptor describes information about a high-speed capable device that would
+// change if the device were operating at the other speed. If not highspeed capable stall this request.
+uint8_t const *tud_descriptor_device_qualifier_cb(void) {
+  return (uint8_t const *) &desc_device_qualifier;
+}
+
+// Invoked when received GET OTHER SEED CONFIGURATION DESCRIPTOR request
+// Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
+// Configuration descriptor in the other speed e.g if high speed then this is for full speed and vice versa
+uint8_t const *tud_descriptor_other_speed_configuration_cb(uint8_t index) {
+  (void) index;// for multiple configurations
+
+  // if link speed is high return fullspeed config, and vice versa
+  return (tud_speed_get() == TUSB_SPEED_HIGH) ? desc_uac1_configuration : desc_uac2_configuration;
+}
+
+#endif // highspeed
+
+// Invoked when received GET CONFIGURATION DESCRIPTOR
+// Application return pointer to descriptor
+// Descriptor contents must exist long enough for transfer to complete
+uint8_t const * tud_descriptor_configuration_cb(uint8_t index) {
+  (void) index; // for multiple configurations
+#if TUD_OPT_HIGH_SPEED
+  // Although we are highspeed, host may be fullspeed.
+  if(tud_speed_get() == TUSB_SPEED_FULL) {
+    return desc_uac1_configuration;
+  } else {
+    return desc_uac2_configuration;
+  }
+#else
+    return desc_uac1_configuration;
+#endif
+}
+
+//--------------------------------------------------------------------+
+// String Descriptors
+//--------------------------------------------------------------------+
+
+// String Descriptor Index
+enum {
+  STRID_LANGID = 0,
+  STRID_MANUFACTURER,
+  STRID_PRODUCT,
+  STRID_SERIAL,
+};
+
+// array of pointer to string descriptors
+static char const *string_desc_arr[] =
+{
+  (const char[]) { 0x09, 0x04 },  // 0: is supported language is English (0x0409)
+  "TinyUSB",                      // 1: Manufacturer
+  "TinyUSB Speaker",              // 2: Product
+  NULL,                           // 3: Serials will use unique ID if possible
+  "UAC2 Speaker",                 // 4: Audio Interface
+  "UAC1 Speaker",                 // 5: UAC1 Audio Interface
+};
+
+static uint16_t _desc_str[32 + 1];
+
+// Invoked when received GET STRING DESCRIPTOR request
+// Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
+uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
+  (void) langid;
+  size_t chr_count;
+
+  switch ( index ) {
+    case STRID_LANGID:
+      memcpy(&_desc_str[1], string_desc_arr[0], 2);
+      chr_count = 1;
+      break;
+
+    case STRID_SERIAL:
+      chr_count = board_usb_get_serial(_desc_str + 1, 32);
+      break;
+
+    default:
+      // Note: the 0xEE index string is a Microsoft OS 1.0 Descriptors.
+      // https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-defined-usb-descriptors
+
+      if ( !(index < sizeof(string_desc_arr) / sizeof(string_desc_arr[0])) ) return NULL;
+
+      const char *str = string_desc_arr[index];
+
+      // Cap at max char
+      chr_count = strlen(str);
+      size_t const max_count = sizeof(_desc_str) / sizeof(_desc_str[0]) - 1; // -1 for string type
+      if ( chr_count > max_count ) chr_count = max_count;
+
+      // Convert ASCII string into UTF-16
+      for ( size_t i = 0; i < chr_count; i++ ) {
+        _desc_str[1 + i] = str[i];
+      }
+      break;
+  }
+
+  // first byte is length (including header), second byte is string type
+  _desc_str[0] = (uint16_t) ((TUSB_DESC_STRING << 8) | (2 * chr_count + 2));
+
+  return _desc_str;
+}

third_party/tinyusb/examples/device/uac2_speaker_fb/src/usb_descriptors.h

@@ -0,0 +1,170 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2023 HiFiPhile
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#ifndef USB_DESCRIPTORS_H_
+#define USB_DESCRIPTORS_H_
+
+//--------------------------------------------------------------------+
+// UAC2 DESCRIPTOR TEMPLATES
+//--------------------------------------------------------------------+
+
+// Defined in TUD_AUDIO20_SPEAKER_STEREO_FB_DESCRIPTOR
+#define UAC2_ENTITY_CLOCK               0x04
+#define UAC2_ENTITY_INPUT_TERMINAL      0x01
+#define UAC2_ENTITY_FEATURE_UNIT        0x02
+#define UAC2_ENTITY_OUTPUT_TERMINAL     0x03
+
+#define TUD_AUDIO20_SPEAKER_STEREO_FB_DESC_LEN (TUD_AUDIO20_DESC_IAD_LEN\
+  + TUD_AUDIO20_DESC_STD_AC_LEN\
+  + TUD_AUDIO20_DESC_CS_AC_LEN\
+  + TUD_AUDIO20_DESC_CLK_SRC_LEN\
+  + TUD_AUDIO20_DESC_INPUT_TERM_LEN\
+  + TUD_AUDIO20_DESC_OUTPUT_TERM_LEN\
+  + TUD_AUDIO20_DESC_FEATURE_UNIT_LEN(2)\
+  + TUD_AUDIO20_DESC_STD_AS_LEN\
+  + TUD_AUDIO20_DESC_STD_AS_LEN\
+  + TUD_AUDIO20_DESC_CS_AS_INT_LEN\
+  + TUD_AUDIO20_DESC_TYPE_I_FORMAT_LEN\
+  + TUD_AUDIO20_DESC_STD_AS_ISO_EP_LEN\
+  + TUD_AUDIO20_DESC_CS_AS_ISO_EP_LEN\
+  + TUD_AUDIO20_DESC_STD_AS_ISO_FB_EP_LEN)
+
+#define TUD_AUDIO20_SPEAKER_STEREO_FB_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epoutsize, _epfb, _epfbsize) \
+  /* Standard Interface Association Descriptor (IAD) */\
+  TUD_AUDIO20_DESC_IAD(/*_firstitf*/ _itfnum, /*_nitfs*/ 0x02, /*_stridx*/ 0x00),\
+  /* Standard AC Interface Descriptor(4.7.1) */\
+  TUD_AUDIO20_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx),\
+  /* Class-Specific AC Interface Header Descriptor(4.7.2) */\
+  TUD_AUDIO20_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO20_FUNC_DESKTOP_SPEAKER, /*_totallen*/ TUD_AUDIO20_DESC_CLK_SRC_LEN+TUD_AUDIO20_DESC_INPUT_TERM_LEN+TUD_AUDIO20_DESC_OUTPUT_TERM_LEN+TUD_AUDIO20_DESC_FEATURE_UNIT_LEN(2), /*_ctrl*/ AUDIO20_CS_AS_INTERFACE_CTRL_LATENCY_POS),\
+  /* Clock Source Descriptor(4.7.2.1) */\
+  TUD_AUDIO20_DESC_CLK_SRC(/*_clkid*/ 0x04, /*_attr*/ AUDIO20_CLOCK_SOURCE_ATT_INT_PRO_CLK, /*_ctrl*/ (AUDIO20_CTRL_RW << AUDIO20_CLOCK_SOURCE_CTRL_CLK_FRQ_POS), /*_assocTerm*/ 0x01,  /*_stridx*/ 0x00),\
+  /* Input Terminal Descriptor(4.7.2.4) */\
+  TUD_AUDIO20_DESC_INPUT_TERM(/*_termid*/ 0x01, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ 0x04, /*_nchannelslogical*/ 0x02, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO20_CTRL_R << AUDIO20_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00),\
+  /* Output Terminal Descriptor(4.7.2.5) */\
+  TUD_AUDIO20_DESC_OUTPUT_TERM(/*_termid*/ 0x03, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ 0x01, /*_srcid*/ 0x02, /*_clkid*/ 0x04, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00),\
+  /* Feature Unit Descriptor(4.7.2.8) */\
+  TUD_AUDIO20_DESC_FEATURE_UNIT(/*_unitid*/ 0x02, /*_srcid*/ 0x01, /*_stridx*/ 0x00, /*_ctrlch0master*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch1*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS, /*_ctrlch2*/ AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_MUTE_POS | AUDIO20_CTRL_RW << AUDIO20_FEATURE_UNIT_CTRL_VOLUME_POS),\
+  /* Standard AS Interface Descriptor(4.9.1) */\
+  /* Interface 1, Alternate 0 - default alternate setting with 0 bandwidth */\
+  TUD_AUDIO20_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00),\
+  /* Standard AS Interface Descriptor(4.9.1) */\
+  /* Interface 1, Alternate 1 - alternate interface for data streaming */\
+  TUD_AUDIO20_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum) + 1), /*_altset*/ 0x01, /*_nEPs*/ 0x02, /*_stridx*/ 0x00),\
+  /* Class-Specific AS Interface Descriptor(4.9.2) */\
+  TUD_AUDIO20_DESC_CS_AS_INT(/*_termid*/ 0x01, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_formattype*/ AUDIO20_FORMAT_TYPE_I, /*_formats*/ AUDIO20_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x02, /*_channelcfg*/ AUDIO20_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
+  /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */\
+  TUD_AUDIO20_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample),\
+  /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */\
+  TUD_AUDIO20_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epoutsize, /*_interval*/ 0x01),\
+  /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */\
+  TUD_AUDIO20_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO20_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO20_CTRL_NONE, /*_lockdelayunit*/ AUDIO20_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_MILLISEC, /*_lockdelay*/ 0x0001),\
+  /* Standard AS Isochronous Feedback Endpoint Descriptor(4.10.2.1) */\
+  TUD_AUDIO20_DESC_STD_AS_ISO_FB_EP(/*_ep*/ _epfb, /*_epsize*/ _epfbsize, /*_interval*/ TUD_OPT_HIGH_SPEED ? 4 : 1)
+
+//--------------------------------------------------------------------+
+// UAC1 DESCRIPTOR TEMPLATES
+//--------------------------------------------------------------------+
+
+// Defined in TUD_AUDIO10_SPEAKER_STEREO_FB_DESCRIPTOR
+#define UAC1_ENTITY_INPUT_TERMINAL      0x01
+#define UAC1_ENTITY_FEATURE_UNIT        0x02
+#define UAC1_ENTITY_OUTPUT_TERMINAL     0x03
+
+#define TUD_AUDIO10_SPEAKER_STEREO_FB_DESC_LEN(_nfreqs) (\
+  + TUD_AUDIO10_DESC_STD_AC_LEN\
+  + TUD_AUDIO10_DESC_CS_AC_LEN(1)\
+  + TUD_AUDIO10_DESC_INPUT_TERM_LEN\
+  + TUD_AUDIO10_DESC_OUTPUT_TERM_LEN\
+  + TUD_AUDIO10_DESC_FEATURE_UNIT_LEN(2)\
+  + TUD_AUDIO10_DESC_STD_AS_LEN\
+  + TUD_AUDIO10_DESC_STD_AS_LEN\
+  + TUD_AUDIO10_DESC_CS_AS_INT_LEN\
+  + TUD_AUDIO10_DESC_TYPE_I_FORMAT_LEN(_nfreqs)\
+  + TUD_AUDIO10_DESC_STD_AS_ISO_EP_LEN\
+  + TUD_AUDIO10_DESC_CS_AS_ISO_EP_LEN\
+  + TUD_AUDIO10_DESC_STD_AS_ISO_SYNC_EP_LEN)
+
+#define TUD_AUDIO10_SPEAKER_STEREO_FB_DESCRIPTOR(_itfnum, _stridx, _nBytesPerSample, _nBitsUsedPerSample, _epout, _epoutsize, _epfb, ...) \
+  /* Standard AC Interface Descriptor(4.3.1) */\
+  TUD_AUDIO10_DESC_STD_AC(/*_itfnum*/ _itfnum, /*_nEPs*/ 0x00, /*_stridx*/ _stridx),\
+  /* Class-Specific AC Interface Header Descriptor(4.3.2) */\
+  TUD_AUDIO10_DESC_CS_AC(/*_bcdADC*/ 0x0100, /*_totallen*/ (TUD_AUDIO10_DESC_INPUT_TERM_LEN+TUD_AUDIO10_DESC_OUTPUT_TERM_LEN+TUD_AUDIO10_DESC_FEATURE_UNIT_LEN(2)), /*_itf*/ ((_itfnum)+1)),\
+  /* Input Terminal Descriptor(4.3.2.1) */\
+  TUD_AUDIO10_DESC_INPUT_TERM(/*_termid*/ 0x01, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_nchannels*/ 0x02, /*_channelcfg*/ AUDIO10_CHANNEL_CONFIG_LEFT_FRONT | AUDIO10_CHANNEL_CONFIG_RIGHT_FRONT, /*_idxchannelnames*/ 0x00, /*_stridx*/ 0x00),\
+  /* Output Terminal Descriptor(4.3.2.2) */\
+  TUD_AUDIO10_DESC_OUTPUT_TERM(/*_termid*/ 0x03, /*_termtype*/ AUDIO_TERM_TYPE_OUT_DESKTOP_SPEAKER, /*_assocTerm*/ 0x00, /*_srcid*/ 0x02, /*_stridx*/ 0x00),\
+  /* Feature Unit Descriptor(4.3.2.5) */\
+  TUD_AUDIO10_DESC_FEATURE_UNIT(/*_unitid*/ 0x02, /*_srcid*/ 0x01, /*_stridx*/ 0x00, /*_ctrlmaster*/ (AUDIO10_FU_CONTROL_BM_MUTE | AUDIO10_FU_CONTROL_BM_VOLUME), /*_ctrlch1*/ (AUDIO10_FU_CONTROL_BM_MUTE | AUDIO10_FU_CONTROL_BM_VOLUME), /*_ctrlch2*/ (AUDIO10_FU_CONTROL_BM_MUTE | AUDIO10_FU_CONTROL_BM_VOLUME)),\
+  /* Standard AS Interface Descriptor(4.5.1) */\
+  /* Interface 1, Alternate 0 - default alternate setting with 0 bandwidth */\
+  TUD_AUDIO10_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum)+1), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x00),\
+  /* Standard AS Interface Descriptor(4.5.1) */\
+  /* Interface 1, Alternate 1 - alternate interface for data streaming */\
+  TUD_AUDIO10_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)((_itfnum)+1), /*_altset*/ 0x01, /*_nEPs*/ 0x02, /*_stridx*/ 0x00),\
+  /* Class-Specific AS Interface Descriptor(4.5.2) */\
+  TUD_AUDIO10_DESC_CS_AS_INT(/*_termid*/ 0x01, /*_delay*/ 0x00, /*_formattype*/ AUDIO10_DATA_FORMAT_TYPE_I_PCM),\
+  /* Type I Format Type Descriptor(2.2.5) */\
+  TUD_AUDIO10_DESC_TYPE_I_FORMAT(/*_nrchannels*/ 0x02, /*_subframesize*/ _nBytesPerSample, /*_bitresolution*/ _nBitsUsedPerSample, /*_freqs*/ __VA_ARGS__),\
+  /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.6.1.1) */\
+  TUD_AUDIO10_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS), /*_maxEPsize*/ _epoutsize, /*_interval*/ 0x01, /*_sync_ep*/ _epfb),\
+  /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.6.1.2) */\
+  TUD_AUDIO10_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO10_CS_AS_ISO_DATA_EP_ATT_SAMPLING_FRQ, /*_lockdelayunits*/ AUDIO10_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000),\
+  /* Standard AS Isochronous Synch Endpoint Descriptor (4.6.2.1) */\
+  TUD_AUDIO10_DESC_STD_AS_ISO_SYNC_EP(/*_ep*/ _epfb, /*_bRefresh*/ 0)
+
+//---------------------------------------------------------------------------+
+//          UAC1 Isochronous Synch Endpoint bRefresh Workaround
+//
+// bRefresh value is set to 0, while UAC1 spec requires it to be between
+// 1 (2 ms) and 9 (512 ms)
+//
+// This value has been tested to work with Windows, macOS and Linux.
+//
+// Rationale:
+// Some USB device controllers (e.g. Synopsys DWC2) require a known transfer
+// interval to manually schedule isochronous IN transfers. For data isochronous
+// endpoints, the bInterval field in the endpoint descriptor is used. However,
+// for synch endpoint it's unclear which field the host uses to determine the
+// transfer interval. Windows and macOS use bRefresh, while Linux uses bInterval.
+//
+// Since bInterval is fixed to 1, if bRefresh is set to 2 then Windows and macOS
+// will schedule the feedback transfer every 4 ms, but Linux will schedule it
+// every 1 ms. DWC2 controller cannot handle this discrepancy without knwowing
+// the actual interval, therefore we set bRefresh to 0 to let the transfer
+// execute every 1 ms, which is the same as bInterval.
+//
+// Rant:
+// WTF USB-IF? Why have two fields that mean the same thing? Why not just use
+// bInterval for both data and synch endpoints? Why is bRefresh even necessary?
+//
+// Note:
+// For the moment DWC2 driver doesn't have proper support for bInterval > 1
+// for isochronous IN endpoints. The implementation would be complex and CPU
+// intensive (cfr.
+// https://github.com/torvalds/linux/blob/master/drivers/usb/dwc2/gadget.c)
+// It MAY work in some cases if you are lucky, but it's not guaranteed.
+//---------------------------------------------------------------------------+
+
+#endif