Fix audiod_get_AS_interface_index in audio class.

Enhance uac2_headset example with multiple sample rates.
Add macro to calculate EP size.

examples/device/uac2_headset/src/main.c

@@ -34,9 +34,11 @@
 // MACRO CONSTANT TYPEDEF PROTOTYPES
 //--------------------------------------------------------------------+
 
-#ifndef AUDIO_SAMPLE_RATE
-#define AUDIO_SAMPLE_RATE     48000
-#endif
+// List of supported sample rates
+const uint32_t sample_rates[]       = {44100, 48000, 88200, 96000};
+uint32_t       current_sample_rate  = 44100;
+
+#define N_SAMPLE_RATES  (sizeof(sample_rates) / 4)
 
 /* Blink pattern
  * - 25 ms   : streaming data
@@ -166,24 +168,30 @@ static bool tud_audio_clock_get_request(uint8_t rhport, audio_control_request_t
 {
   TU_ASSERT(request->bEntityID == UAC2_ENTITY_CLOCK);
 
-  // Example supports only single frequency, same value will be used for current value and range
   if (request->bControlSelector == AUDIO_CS_CTRL_SAM_FREQ)
   {
     if (request->bRequest == AUDIO_CS_REQ_CUR)
     {
-      TU_LOG2("Clock get current freq %u\r\n", AUDIO_SAMPLE_RATE);
+      TU_LOG1("Clock get current freq %u\r\n", current_sample_rate);
 
-      audio_control_cur_4_t curf = { tu_htole32(AUDIO_SAMPLE_RATE) };
+      audio_control_cur_4_t curf = { tu_htole32(current_sample_rate) };
       return tud_audio_buffer_and_schedule_control_xfer(rhport, (tusb_control_request_t const *)request, &curf, sizeof(curf));
     }
     else if (request->bRequest == AUDIO_CS_REQ_RANGE)
     {
-      audio_control_range_4_n_t(1) rangef =
+      audio_control_range_4_n_t(N_SAMPLE_RATES) rangef =
       {
-        .wNumSubRanges = tu_htole16(1),
-        .subrange[0] = { tu_htole32(AUDIO_SAMPLE_RATE), tu_htole32(AUDIO_SAMPLE_RATE), 0}
+        .wNumSubRanges = tu_htole16(N_SAMPLE_RATES)
       };
-      TU_LOG2("Clock get freq range (%d, %d, %d)\r\n", (int)rangef.subrange[0].bMin, (int)rangef.subrange[0].bMax, (int)rangef.subrange[0].bRes);
+      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 = sample_rates[i];
+        rangef.subrange[i].bMax = 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, (tusb_control_request_t const *)request, &rangef, sizeof(rangef));
     }
   }
@@ -191,7 +199,7 @@ static bool tud_audio_clock_get_request(uint8_t rhport, audio_control_request_t
            request->bRequest == AUDIO_CS_REQ_CUR)
   {
     audio_control_cur_1_t cur_valid = { .bCur = 1 };
-    TU_LOG2("Clock get is valid %u\r\n", cur_valid.bCur);
+    TU_LOG1("Clock get is valid %u\r\n", cur_valid.bCur);
     return tud_audio_buffer_and_schedule_control_xfer(rhport, (tusb_control_request_t const *)request, &cur_valid, sizeof(cur_valid));
   }
   TU_LOG1("Clock get request not supported, entity = %u, selector = %u, request = %u\r\n",
@@ -199,6 +207,32 @@ static bool tud_audio_clock_get_request(uint8_t rhport, audio_control_request_t
   return false;
 }
 
+// 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_ASSERT(request->bEntityID == UAC2_ENTITY_SPK_FEATURE_UNIT);
+  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;
+  }
+}
+
 // Helper for feature unit get requests
 static bool tud_audio_feature_unit_get_request(uint8_t rhport, audio_control_request_t const *request)
 {
@@ -207,7 +241,7 @@ static bool tud_audio_feature_unit_get_request(uint8_t rhport, audio_control_req
   if (request->bControlSelector == AUDIO_FU_CTRL_MUTE && request->bRequest == AUDIO_CS_REQ_CUR)
   {
     audio_control_cur_1_t mute1 = { .bCur = mute[request->bChannelNumber] };
-    TU_LOG2("Get channel %u mute %d\r\n", request->bChannelNumber, mute1.bCur);
+    TU_LOG1("Get channel %u mute %d\r\n", request->bChannelNumber, mute1.bCur);
     return tud_audio_buffer_and_schedule_control_xfer(rhport, (tusb_control_request_t const *)request, &mute1, sizeof(mute1));
   }
   else if (UAC2_ENTITY_SPK_FEATURE_UNIT && request->bControlSelector == AUDIO_FU_CTRL_VOLUME)
@@ -218,14 +252,14 @@ static bool tud_audio_feature_unit_get_request(uint8_t rhport, audio_control_req
         .wNumSubRanges = tu_htole16(1),
         .subrange[0] = { .bMin = tu_htole16(-VOLUME_CTRL_50_DB), tu_htole16(VOLUME_CTRL_0_DB), tu_htole16(256) }
       };
-      TU_LOG2("Get channel %u volume range (%d, %d, %u) dB\r\n", request->bChannelNumber,
+      TU_LOG1("Get channel %u volume range (%d, %d, %u) dB\r\n", request->bChannelNumber,
               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, (tusb_control_request_t const *)request, &range_vol, sizeof(range_vol));
     }
     else if (request->bRequest == AUDIO_CS_REQ_CUR)
     {
       audio_control_cur_2_t cur_vol = { .bCur = tu_htole16(volume[request->bChannelNumber]) };
-      TU_LOG2("Get channel %u volume %u dB\r\n", request->bChannelNumber, cur_vol.bCur);
+      TU_LOG1("Get channel %u volume %d dB\r\n", request->bChannelNumber, cur_vol.bCur / 256);
       return tud_audio_buffer_and_schedule_control_xfer(rhport, (tusb_control_request_t const *)request, &cur_vol, sizeof(cur_vol));
     }
   }
@@ -249,7 +283,7 @@ static bool tud_audio_feature_unit_set_request(uint8_t rhport, audio_control_req
 
     mute[request->bChannelNumber] = ((audio_control_cur_1_t *)buf)->bCur;
 
-    TU_LOG2("Set channel %d Mute: %d\r\n", request->bChannelNumber, mute[request->bChannelNumber]);
+    TU_LOG1("Set channel %d Mute: %d\r\n", request->bChannelNumber, mute[request->bChannelNumber]);
 
     return true;
   }
@@ -259,7 +293,7 @@ static bool tud_audio_feature_unit_set_request(uint8_t rhport, audio_control_req
 
     volume[request->bChannelNumber] = ((audio_control_cur_2_t const *)buf)->bCur;
 
-    TU_LOG2("Set channel %d volume: %d dB\r\n", request->bChannelNumber, volume[request->bChannelNumber] / 256);
+    TU_LOG1("Set channel %d volume: %d dB\r\n", request->bChannelNumber, volume[request->bChannelNumber] / 256);
 
     return true;
   }
@@ -299,7 +333,8 @@ bool tud_audio_set_req_entity_cb(uint8_t rhport, tusb_control_request_t const *p
 
   if (request->bEntityID == UAC2_ENTITY_SPK_FEATURE_UNIT)
     return tud_audio_feature_unit_set_request(rhport, request, buf);
-
+  if (request->bEntityID == UAC2_ENTITY_CLOCK)
+    return tud_audio_clock_set_request(rhport, request, buf);
   TU_LOG1("Set request not handled, entity = %d, selector = %d, request = %d\r\n",
           request->bEntityID, request->bControlSelector, request->bRequest);
 

examples/device/uac2_headset/src/tusb_config.h

@@ -93,13 +93,12 @@ extern "C" {
 //--------------------------------------------------------------------
 // AUDIO CLASS DRIVER CONFIGURATION
 //--------------------------------------------------------------------
-#define CFG_TUD_AUDIO_IN_PATH                     (CFG_TUD_AUDIO)
-#define CFG_TUD_AUDIO_OUT_PATH                    (CFG_TUD_AUDIO)
 
 //#define CFG_TUD_AUDIO_FUNC_1_DESC_LEN                       220       // This equals TUD_AUDIO_HEADSET_STEREO_DESC_LEN, however, including it from usb_descriptors.h is not possible due to some strange include hassle
 #define CFG_TUD_AUDIO_FUNC_1_DESC_LEN                       TUD_AUDIO_HEADSET_STEREO_DESC_LEN
 
 // Audio format type I specifications
+#define CFG_TUD_AUDIO_FUNC_1_N_MAX_SAMPLE_RATE              96000
 #define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX                  1
 #define CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_TX          2
 #define CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX                  2
@@ -108,18 +107,18 @@ extern "C" {
 
 // EP and buffer size - for isochronous EP´s, the buffer and EP size are equal (different sizes would not make sense)
 #define CFG_TUD_AUDIO_ENABLE_EP_IN                1
-#define CFG_TUD_AUDIO_EP_SZ_IN                    (CFG_TUD_AUDIO_IN_PATH * (48 + 1) * (CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_TX) * (CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX)) // 48 Samples (48 kHz) x 2 Bytes/Sample x n Channels
+#define CFG_TUD_AUDIO_EP_SZ_IN                    TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_N_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_TX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX) // 48 Samples (48 kHz) x 2 Bytes/Sample x n Channels
 #define CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ      CFG_TUD_AUDIO_EP_SZ_IN
 #define CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX         CFG_TUD_AUDIO_EP_SZ_IN                  // Maximum EP IN size for all AS alternate settings used
 
 // EP and buffer size - for isochronous EP´s, the buffer and EP size are equal (different sizes would not make sense)
 #define CFG_TUD_AUDIO_ENABLE_EP_OUT               1
-#define CFG_TUD_AUDIO_EP_OUT_SZ                   (CFG_TUD_AUDIO_OUT_PATH * ((48 + CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP) * (CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX) * (CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX))) // N Samples (N kHz) x 2 Bytes/Sample x n Channels
-#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ     CFG_TUD_AUDIO_EP_OUT_SZ*3
-#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX        CFG_TUD_AUDIO_EP_OUT_SZ                 // Maximum EP IN size for all AS alternate settings used
+#define CFG_TUD_AUDIO_EP_SZ_OUT                   TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_N_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX) // N Samples (N kHz) x 2 Bytes/Sample x n Channels
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ     CFG_TUD_AUDIO_EP_SZ_OUT*3
+#define CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX        CFG_TUD_AUDIO_EP_SZ_OUT                 // Maximum EP IN size for all AS alternate settings used
 
 // Number of Standard AS Interface Descriptors (4.9.1) defined per audio function - this is required to be able to remember the current alternate settings of these interfaces - We restrict us here to have a constant number for all audio functions (which means this has to be the maximum number of AS interfaces an audio function has and a second audio function with less AS interfaces just wastes a few bytes)
-#define CFG_TUD_AUDIO_FUNC_1_N_AS_INT 	          1
+#define CFG_TUD_AUDIO_FUNC_1_N_AS_INT 	          2
 
 // Size of control request buffer
 #define CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ	64

examples/device/uac2_headset/src/usb_descriptors.c

@@ -93,7 +93,7 @@ uint8_t const desc_configuration[] =
     TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, TUSB_DESC_CONFIG_ATT_REMOTE_WAKEUP, 100),
 
     // Interface number, string index, EP Out & EP In address, EP size
-    TUD_AUDIO_HEADSET_STEREO_DESCRIPTOR(2, 2, 16, EPNUM_AUDIO, CFG_TUD_AUDIO_EP_OUT_SZ, EPNUM_AUDIO | 0x80, CFG_TUD_AUDIO_EP_SZ_IN)
+    TUD_AUDIO_HEADSET_STEREO_DESCRIPTOR(2, 2, 16, EPNUM_AUDIO, CFG_TUD_AUDIO_EP_SZ_OUT, EPNUM_AUDIO | 0x80, CFG_TUD_AUDIO_EP_SZ_IN)
 };
 
 // Invoked when received GET CONFIGURATION DESCRIPTOR

examples/device/uac2_headset/src/usb_descriptors.h

@@ -77,7 +77,7 @@ enum
     /* Class-Specific AC Interface Header Descriptor(4.7.2) */\
     TUD_AUDIO_DESC_CS_AC(/*_bcdADC*/ 0x0200, /*_category*/ AUDIO_FUNC_HEADSET, /*_totallen*/ TUD_AUDIO_DESC_CLK_SRC_LEN+TUD_AUDIO_DESC_FEATURE_UNIT_TWO_CHANNEL_LEN+TUD_AUDIO_DESC_INPUT_TERM_LEN+TUD_AUDIO_DESC_OUTPUT_TERM_LEN+TUD_AUDIO_DESC_INPUT_TERM_LEN+TUD_AUDIO_DESC_OUTPUT_TERM_LEN, /*_ctrl*/ AUDIO_CS_AS_INTERFACE_CTRL_LATENCY_POS),\
     /* Clock Source Descriptor(4.7.2.1) */\
-    TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ UAC2_ENTITY_CLOCK, /*_attr*/ 3, /*_ctrl*/ 5, /*_assocTerm*/ 0x00,  /*_stridx*/ 0x00),    \
+    TUD_AUDIO_DESC_CLK_SRC(/*_clkid*/ UAC2_ENTITY_CLOCK, /*_attr*/ 3, /*_ctrl*/ 7, /*_assocTerm*/ 0x00,  /*_stridx*/ 0x00),    \
     /* Input Terminal Descriptor(4.7.2.4) */\
     TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ UAC2_ENTITY_SPK_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_clkid*/ UAC2_ENTITY_CLOCK, /*_nchannelslogical*/ 0x02, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00),\
     /* Feature Unit Descriptor(4.7.2.8) */\
@@ -99,21 +99,21 @@ enum
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */\
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample),\
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */\
-    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ADAPTIVE | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epoutsize, /*_interval*/ (CFG_TUSB_RHPORT0_MODE & OPT_MODE_HIGH_SPEED) ? 0x04 : 0x01),\
+    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epoutsize, /*_interval*/ 0x01),\
     /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */\
     TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_MILLISEC, /*_lockdelay*/ 0x0001),\
     /* Standard AS Interface Descriptor(4.9.1) */\
     /* Interface 2, Alternate 0 - default alternate setting with 0 bandwidth */\
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)(ITF_NUM_AUDIO_STREAMING_MIC), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x04),\
     /* Standard AS Interface Descriptor(4.9.1) */\
-    /* Interface 1, Alternate 1 - alternate interface for data streaming */\
+    /* Interface 2, Alternate 1 - alternate interface for data streaming */\
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)(ITF_NUM_AUDIO_STREAMING_MIC), /*_altset*/ 0x01, /*_nEPs*/ 0x01, /*_stridx*/ 0x04),\
     /* Class-Specific AS Interface Descriptor(4.9.2) */\
     TUD_AUDIO_DESC_CS_AS_INT(/*_termid*/ UAC2_ENTITY_MIC_OUTPUT_TERMINAL, /*_ctrl*/ AUDIO_CTRL_NONE, /*_formattype*/ AUDIO_FORMAT_TYPE_I, /*_formats*/ AUDIO_DATA_FORMAT_TYPE_I_PCM, /*_nchannelsphysical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_stridx*/ 0x00),\
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */\
     TUD_AUDIO_DESC_TYPE_I_FORMAT(_nBytesPerSample, _nBitsUsedPerSample),\
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */\
-    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ASYNCHRONOUS | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epinsize, /*_interval*/ (CFG_TUSB_RHPORT0_MODE & OPT_MODE_HIGH_SPEED) ? 0x04 : 0x01),\
+    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ _epinsize, /*_interval*/ 0x01),\
     /* Class-Specific AS Isochronous Audio Data Endpoint Descriptor(4.10.1.2) */\
     TUD_AUDIO_DESC_CS_AS_ISO_EP(/*_attr*/ AUDIO_CS_AS_ISO_DATA_EP_ATT_NON_MAX_PACKETS_OK, /*_ctrl*/ AUDIO_CTRL_NONE, /*_lockdelayunit*/ AUDIO_CS_AS_ISO_DATA_EP_LOCK_DELAY_UNIT_UNDEFINED, /*_lockdelay*/ 0x0000)\
 

src/class/audio/audio_device.c

@@ -1997,15 +1997,17 @@ static bool audiod_get_AS_interface_index(uint8_t itf, audiod_function_t * audio
     while (p_desc < p_desc_end)
     {
       // We assume the number of alternate settings is increasing thus we return the index of alternate setting zero!
-      if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE && ((tusb_desc_interface_t const * )p_desc)->bInterfaceNumber == itf)
+      if (tu_desc_type(p_desc) == TUSB_DESC_INTERFACE && ((tusb_desc_interface_t const * )p_desc)->bAlternateSetting == 0)
       {
-        *idxItf = tmp;
-        *pp_desc_int = p_desc;
-        return true;
+        if (((tusb_desc_interface_t const * )p_desc)->bInterfaceNumber == itf)
+        {
+          *idxItf = tmp;
+          *pp_desc_int = p_desc;
+          return true;
+        }
+        // Increase index, bytes read, and pointer
+        tmp++;
       }
-
-      // Increase index, bytes read, and pointer
-      tmp++;
       p_desc = tu_desc_next(p_desc);
     }
   }

src/device/usbd.h

@@ -542,6 +542,11 @@ TU_ATTR_WEAK bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb
   /* Standard AS Isochronous Feedback Endpoint Descriptor(4.10.2.1) */\
   TUD_AUDIO_DESC_STD_AS_ISO_FB_EP(/*_ep*/ _epfb, /*_interval*/ 1)\
 
+//   Calculate wMaxPacketSize of Endpoints
+#define TUD_AUDIO_EP_SIZE(_maxFrequency, _nBytesPerSample, _nChannels) \
+    ((((_maxFrequency + ((CFG_TUSB_RHPORT0_MODE & OPT_MODE_HIGH_SPEED) ? 7999 : 999)) / ((CFG_TUSB_RHPORT0_MODE & OPT_MODE_HIGH_SPEED) ? 8000 : 1000)) + 1) * _nBytesPerSample * _nChannels)
+
+
 //------------- TUD_USBTMC/USB488 -------------//
 #define TUD_USBTMC_APP_CLASS    (TUSB_CLASS_APPLICATION_SPECIFIC)
 #define TUD_USBTMC_APP_SUBCLASS 0x03u