Merge pull request #1702 from battlesnake/uac2-interrupt-endpoint

UAC2 supports interrupt-endpoint for providing control-change notifications to the host

examples/device/uac2_headset/src/main.c

@@ -96,6 +96,7 @@ uint8_t current_resolution;
 
 void led_blinking_task(void);
 void audio_task(void);
+void audio_control_task(void);
 
 /*------------- MAIN -------------*/
 int main(void)
@@ -115,6 +116,7 @@ int main(void)
   {
     tud_task(); // TinyUSB device task
     audio_task();
+    audio_control_task();
     led_blinking_task();
   }
 }
@@ -428,6 +430,45 @@ void audio_task(void)
   }
 }
 
+void audio_control_task(void)
+{
+  // Press on-board button to control volume
+  // Open host volume control, volume should switch between 10% and 100%
+
+  // Poll every 50ms
+  const uint32_t interval_ms = 50;
+  static uint32_t start_ms = 0;
+  static uint32_t btn_prev = 0;
+
+  if ( board_millis() - start_ms < interval_ms) return; // not enough time
+  start_ms += interval_ms;
+
+  uint32_t btn = board_button_read();
+
+  if (!btn_prev && btn)
+  {
+    // Adjust volume between 0dB (100%) and -30dB (10%)
+    for (int i = 0; i < CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX + 1; i++)
+    {
+      volume[i] = volume[i] == 0 ? -VOLUME_CTRL_30_DB : 0;
+    }
+
+    // 6.1 Interrupt Data Message
+    const audio_interrupt_data_t data = {
+      .bInfo = 0,                                       // Class-specific interrupt, originated from an interface
+      .bAttribute = AUDIO_CS_REQ_CUR,                   // Caused by current settings
+      .wValue_cn_or_mcn = 0,                            // CH0: master volume
+      .wValue_cs = AUDIO_FU_CTRL_VOLUME,                // Volume change
+      .wIndex_ep_or_int = 0,                            // From the interface itself
+      .wIndex_entity_id = UAC2_ENTITY_SPK_FEATURE_UNIT, // From feature unit
+    };
+
+    tud_audio_int_write(&data);
+  }
+
+  btn_prev = btn;
+}
+
 //--------------------------------------------------------------------+
 // BLINKING TASK
 //--------------------------------------------------------------------+

examples/device/uac2_headset/src/tusb_config.h

@@ -105,6 +105,9 @@ extern "C" {
 // AUDIO CLASS DRIVER CONFIGURATION
 //--------------------------------------------------------------------
 
+// Allow volume controlled by on-baord button
+#define CFG_TUD_AUDIO_ENABLE_INTERRUPT_EP                            1
+
 #define CFG_TUD_AUDIO_FUNC_1_DESC_LEN                                TUD_AUDIO_HEADSET_STEREO_DESC_LEN
 
 // How many formats are used, need to adjust USB descriptor if changed

examples/device/uac2_headset/src/usb_descriptors.c

@@ -82,27 +82,32 @@ uint8_t const * tud_descriptor_device_cb(void)
   // 0 control, 1 In, 2 Bulk, 3 Iso, 4 In etc ...
   #define EPNUM_AUDIO_IN    0x03
   #define EPNUM_AUDIO_OUT   0x03
+  #define EPNUM_AUDIO_INT   0x01
 
 #elif CFG_TUSB_MCU == OPT_MCU_NRF5X
   // ISO endpoints for NRF5x are fixed to 0x08 (0x88)
   #define EPNUM_AUDIO_IN    0x08
   #define EPNUM_AUDIO_OUT   0x08
+  #define EPNUM_AUDIO_INT   0x01
 
 #elif CFG_TUSB_MCU == OPT_MCU_SAMG  || CFG_TUSB_MCU ==  OPT_MCU_SAMX7X
   // SAMG & SAME70 don't support a same endpoint number with different direction IN and OUT
   //    e.g EP1 OUT & EP1 IN cannot exist together
   #define EPNUM_AUDIO_IN    0x01
   #define EPNUM_AUDIO_OUT   0x02
+  #define EPNUM_AUDIO_INT   0x03
 
 #elif CFG_TUSB_MCU == OPT_MCU_FT90X || CFG_TUSB_MCU == OPT_MCU_FT93X
   // FT9XX doesn't support a same endpoint number with different direction IN and OUT
   //    e.g EP1 OUT & EP1 IN cannot exist together
   #define EPNUM_AUDIO_IN    0x01
   #define EPNUM_AUDIO_OUT   0x02
+  #define EPNUM_AUDIO_INT   0x03
 
 #else
   #define EPNUM_AUDIO_IN    0x01
   #define EPNUM_AUDIO_OUT   0x01
+  #define EPNUM_AUDIO_INT   0x02
 #endif
 
 uint8_t const desc_configuration[] =
@@ -111,7 +116,7 @@ uint8_t const desc_configuration[] =
     TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x00, 100),
 
     // Interface number, string index, EP Out & EP In address, EP size
-    TUD_AUDIO_HEADSET_STEREO_DESCRIPTOR(2, EPNUM_AUDIO_OUT, EPNUM_AUDIO_IN | 0x80)
+    TUD_AUDIO_HEADSET_STEREO_DESCRIPTOR(2, EPNUM_AUDIO_OUT, EPNUM_AUDIO_IN | 0x80, EPNUM_AUDIO_INT | 0x80)
 };
 
 // Invoked when received GET CONFIGURATION DESCRIPTOR

examples/device/uac2_headset/src/usb_descriptors.h

@@ -55,6 +55,7 @@ enum
     + TUD_AUDIO_DESC_OUTPUT_TERM_LEN\
     + TUD_AUDIO_DESC_INPUT_TERM_LEN\
     + TUD_AUDIO_DESC_OUTPUT_TERM_LEN\
+    + TUD_AUDIO_DESC_STD_AC_INT_EP_LEN\
     /* Interface 1, Alternate 0 */\
     + TUD_AUDIO_DESC_STD_AS_INT_LEN\
     /* Interface 1, Alternate 1 */\
@@ -84,11 +85,11 @@ enum
     + TUD_AUDIO_DESC_STD_AS_ISO_EP_LEN\
     + TUD_AUDIO_DESC_CS_AS_ISO_EP_LEN)
 
-#define TUD_AUDIO_HEADSET_STEREO_DESCRIPTOR(_stridx, _epout, _epin) \
+#define TUD_AUDIO_HEADSET_STEREO_DESCRIPTOR(_stridx, _epout, _epin, _epint) \
     /* Standard Interface Association Descriptor (IAD) */\
     TUD_AUDIO_DESC_IAD(/*_firstitf*/ ITF_NUM_AUDIO_CONTROL, /*_nitfs*/ ITF_NUM_TOTAL, /*_stridx*/ 0x00),\
     /* Standard AC Interface Descriptor(4.7.1) */\
-    TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ ITF_NUM_AUDIO_CONTROL, /*_nEPs*/ 0x00, /*_stridx*/ _stridx),\
+    TUD_AUDIO_DESC_STD_AC(/*_itfnum*/ ITF_NUM_AUDIO_CONTROL, /*_nEPs*/ 0x01, /*_stridx*/ _stridx),\
     /* 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) */\
@@ -103,6 +104,8 @@ enum
     TUD_AUDIO_DESC_INPUT_TERM(/*_termid*/ UAC2_ENTITY_MIC_INPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_IN_GENERIC_MIC, /*_assocTerm*/ 0x00, /*_clkid*/ UAC2_ENTITY_CLOCK, /*_nchannelslogical*/ 0x01, /*_channelcfg*/ AUDIO_CHANNEL_CONFIG_NON_PREDEFINED, /*_idxchannelnames*/ 0x00, /*_ctrl*/ 0 * (AUDIO_CTRL_R << AUDIO_IN_TERM_CTRL_CONNECTOR_POS), /*_stridx*/ 0x00),\
     /* Output Terminal Descriptor(4.7.2.5) */\
     TUD_AUDIO_DESC_OUTPUT_TERM(/*_termid*/ UAC2_ENTITY_MIC_OUTPUT_TERMINAL, /*_termtype*/ AUDIO_TERM_TYPE_USB_STREAMING, /*_assocTerm*/ 0x00, /*_srcid*/ UAC2_ENTITY_MIC_INPUT_TERMINAL, /*_clkid*/ UAC2_ENTITY_CLOCK, /*_ctrl*/ 0x0000, /*_stridx*/ 0x00),\
+    /* Standard AC Interrupt Endpoint Descriptor(4.8.2.1) */\
+    TUD_AUDIO_DESC_STD_AC_INT_EP(/*_ep*/ _epint, /*_interval*/ 0x01), \
     /* Standard AS Interface Descriptor(4.9.1) */\
     /* Interface 1, Alternate 0 - default alternate setting with 0 bandwidth */\
     TUD_AUDIO_DESC_STD_AS_INT(/*_itfnum*/ (uint8_t)(ITF_NUM_AUDIO_STREAMING_SPK), /*_altset*/ 0x00, /*_nEPs*/ 0x00, /*_stridx*/ 0x05),\
@@ -114,7 +117,7 @@ enum
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */\
     TUD_AUDIO_DESC_TYPE_I_FORMAT(CFG_TUD_AUDIO_FUNC_1_FORMAT_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_FORMAT_1_RESOLUTION_RX),\
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */\
-    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t) (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ADAPTIVE | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX), /*_interval*/ 0x01),\
+    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ADAPTIVE | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_1_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX), /*_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),\
     /* Interface 1, Alternate 2 - alternate interface for data streaming */\
@@ -124,7 +127,7 @@ enum
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */\
     TUD_AUDIO_DESC_TYPE_I_FORMAT(CFG_TUD_AUDIO_FUNC_1_FORMAT_2_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_FORMAT_2_RESOLUTION_RX),\
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */\
-    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t) (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ADAPTIVE | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_2_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX), /*_interval*/ 0x01),\
+    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epout, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ADAPTIVE | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_2_N_BYTES_PER_SAMPLE_RX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_RX), /*_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) */\
@@ -138,7 +141,7 @@ enum
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */\
     TUD_AUDIO_DESC_TYPE_I_FORMAT(CFG_TUD_AUDIO_FUNC_1_FORMAT_1_N_BYTES_PER_SAMPLE_TX, CFG_TUD_AUDIO_FUNC_1_FORMAT_1_RESOLUTION_TX),\
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */\
-    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ASYNCHRONOUS | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_1_N_BYTES_PER_SAMPLE_TX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX), /*_interval*/ 0x01),\
+    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_1_N_BYTES_PER_SAMPLE_TX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX), /*_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),\
     /* Interface 2, Alternate 2 - alternate interface for data streaming */\
@@ -148,7 +151,7 @@ enum
     /* Type I Format Type Descriptor(2.3.1.6 - Audio Formats) */\
     TUD_AUDIO_DESC_TYPE_I_FORMAT(CFG_TUD_AUDIO_FUNC_1_FORMAT_2_N_BYTES_PER_SAMPLE_TX, CFG_TUD_AUDIO_FUNC_1_FORMAT_2_RESOLUTION_TX),\
     /* Standard AS Isochronous Audio Data Endpoint Descriptor(4.10.1.1) */\
-    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ASYNCHRONOUS | TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_2_N_BYTES_PER_SAMPLE_TX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX), /*_interval*/ 0x01),\
+    TUD_AUDIO_DESC_STD_AS_ISO_EP(/*_ep*/ _epin, /*_attr*/ (uint8_t) ((uint8_t)TUSB_XFER_ISOCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_ASYNCHRONOUS | (uint8_t)TUSB_ISO_EP_ATT_DATA), /*_maxEPsize*/ TUD_AUDIO_EP_SIZE(CFG_TUD_AUDIO_FUNC_1_MAX_SAMPLE_RATE, CFG_TUD_AUDIO_FUNC_1_FORMAT_2_N_BYTES_PER_SAMPLE_TX, CFG_TUD_AUDIO_FUNC_1_N_CHANNELS_TX), /*_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.h

@@ -924,6 +924,31 @@ typedef struct TU_ATTR_PACKED {
     } subrange[numSubRanges];                   \
 }
 
+// 6.1 Interrupt Data Message Format
+typedef struct TU_ATTR_PACKED
+{
+  uint8_t bInfo;
+  uint8_t bAttribute;
+  union
+  {
+    uint16_t wValue;
+    struct
+    {
+      uint8_t wValue_cn_or_mcn;
+      uint8_t wValue_cs;
+    };
+  };
+  union
+  {
+    uint16_t wIndex;
+    struct
+    {
+      uint8_t wIndex_ep_or_int;
+      uint8_t wIndex_entity_id;
+    };
+  };
+} audio_interrupt_data_t;
+
 /** @} */
 
 #ifdef __cplusplus

src/class/audio/audio_device.c

@@ -301,10 +301,12 @@ typedef struct
 
 #endif
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-  uint8_t ep_int_ctr;           // Audio control interrupt EP.
+#if CFG_TUD_AUDIO_ENABLE_INTERRUPT_EP
+  uint8_t ep_int;               // Audio control interrupt EP.
 #endif
 
+  bool mounted;                 // Device opened
+
   /*------------- From this point, data is not cleared by bus reset -------------*/
 
   uint16_t desc_length;         // Length of audio function descriptor
@@ -358,8 +360,8 @@ typedef struct
 #endif
 
   // Audio control interrupt buffer - no FIFO - 6 Bytes according to UAC 2 specification (p. 74)
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-  CFG_TUSB_MEM_ALIGN uint8_t ep_int_ctr_buf[CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE];
+#if CFG_TUD_AUDIO_ENABLE_INTERRUPT_EP
+  CFG_TUSB_MEM_ALIGN uint8_t ep_int_buf[6];
 #endif
 
   // Decoding parameters - parameters are set when alternate AS interface is set by host
@@ -486,23 +488,7 @@ bool tud_audio_n_mounted(uint8_t func_id)
   TU_VERIFY(func_id < CFG_TUD_AUDIO);
   audiod_function_t* audio = &_audiod_fct[func_id];
 
-#if CFG_TUD_AUDIO_ENABLE_EP_OUT
-  if (audio->ep_out == 0) return false;
-#endif
-
-#if CFG_TUD_AUDIO_ENABLE_EP_IN
-  if (audio->ep_in == 0) return false;
-#endif
-
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-  if (audio->ep_int_ctr == 0) return false;
-#endif
-
-#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-  if (audio->ep_fb == 0) return false;
-#endif
-
-  return true;
+  return audio->mounted;
 }
 
 //--------------------------------------------------------------------+
@@ -825,24 +811,30 @@ tu_fifo_t* tud_audio_n_get_tx_support_ff(uint8_t func_id, uint8_t ff_idx)
 #endif
 
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-
-// If no interrupt transmit is pending bytes get written into buffer and a transmit is scheduled - once transmit completed tud_audio_int_ctr_done_cb() is called in inform user
-uint16_t tud_audio_int_ctr_n_write(uint8_t func_id, uint8_t const* buffer, uint16_t len)
+#if CFG_TUD_AUDIO_ENABLE_INTERRUPT_EP
+// If no interrupt transmit is pending bytes get written into buffer and a transmit is scheduled - once transmit completed tud_audio_int_done_cb() is called in inform user
+bool tud_audio_int_n_write(uint8_t func_id, const audio_interrupt_data_t * data)
 {
   TU_VERIFY(func_id < CFG_TUD_AUDIO && _audiod_fct[func_id].p_desc != NULL);
 
-  // We write directly into the EP's buffer - abort if previous transfer not complete
-  TU_VERIFY(!usbd_edpt_busy(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int_ctr));
+  TU_VERIFY(_audiod_fct[func_id].ep_int != 0);
 
-  TU_VERIFY(tu_memcpy_s(_audiod_fct[func_id].ep_int_ctr_buf, CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE,  buffer, len)==0);
+  // We write directly into the EP's buffer - abort if previous transfer not complete
+  TU_VERIFY(usbd_edpt_claim(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int));
 
-  // Schedule transmit
-  TU_VERIFY(usbd_edpt_xfer(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int_ctr, _audiod_fct[func_id].ep_int_ctr_buf, len));
+  // Check length
+  if (tu_memcpy_s(_audiod_fct[func_id].ep_int_buf, sizeof(_audiod_fct[func_id].ep_int_buf),  data, sizeof(audio_interrupt_data_t)) == 0)
+  {
+    // Schedule transmit
+    TU_ASSERT(usbd_edpt_xfer(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int, _audiod_fct[func_id].ep_int_buf, sizeof(_audiod_fct[func_id].ep_int_buf)), 0);
+  } else
+  {
+    // Release endpoint since we don't make any transfer
+    usbd_edpt_release(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int);
+  }
 
   return true;
 }
-
 #endif
 
 // This function is called once a transmit of an audio packet was successfully completed. Here, we encode samples and place it in IN EP's buffer for next transmission.
@@ -1447,10 +1439,11 @@ uint16_t audiod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
   // Verify version is correct - this check can be omitted
   TU_VERIFY(itf_desc->bInterfaceProtocol == AUDIO_INT_PROTOCOL_CODE_V2);
 
-  // Verify interrupt control EP is enabled if demanded by descriptor - this should be best some static check however - this check can be omitted
-  if (itf_desc->bNumEndpoints == 1) // 0 or 1 EPs are allowed
+  // Verify interrupt control EP is enabled if demanded by descriptor
+  TU_ASSERT(itf_desc->bNumEndpoints <= 1); // 0 or 1 EPs are allowed
+  if (itf_desc->bNumEndpoints == 1)
   {
-    TU_VERIFY(CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN > 0);
+    TU_ASSERT(CFG_TUD_AUDIO_ENABLE_INTERRUPT_EP);
   }
 
   // Alternate setting MUST be zero - this check can be omitted
@@ -1594,6 +1587,32 @@ uint16_t audiod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
       }
 #endif // CFG_TUD_AUDIO_EP_IN_FLOW_CONTROL
 
+#if CFG_TUD_AUDIO_ENABLE_INTERRUPT_EP
+      {
+        uint8_t const *p_desc = _audiod_fct[i].p_desc;
+        uint8_t const *p_desc_end = p_desc + _audiod_fct[i].desc_length - TUD_AUDIO_DESC_IAD_LEN;
+        // Condition modified from p_desc < p_desc_end to prevent gcc>=12 strict-overflow warning
+        while (p_desc_end - p_desc > 0)
+        {
+          // For each endpoint
+          if (tu_desc_type(p_desc) == TUSB_DESC_ENDPOINT)
+          {
+            tusb_desc_endpoint_t const* desc_ep = (tusb_desc_endpoint_t const *) p_desc;
+            uint8_t const ep_addr = desc_ep->bEndpointAddress;
+            // If endpoint is input-direction and interrupt-type
+            if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN && desc_ep->bmAttributes.xfer == TUSB_XFER_INTERRUPT)
+            {
+              // Store endpoint number and open endpoint
+              _audiod_fct[i].ep_int = ep_addr;
+              TU_ASSERT(usbd_edpt_open(_audiod_fct[i].rhport, desc_ep));
+            }
+          }
+          p_desc = tu_desc_next(p_desc);
+        }
+      }
+#endif
+
+      _audiod_fct[i].mounted = true;
       break;
     }
   }
@@ -2120,10 +2139,10 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
   {
     audiod_function_t* audio = &_audiod_fct[func_id];
 
-#if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
+#if CFG_TUD_AUDIO_ENABLE_INTERRUPT_EP
 
     // Data transmission of control interrupt finished
-    if (audio->ep_int_ctr == ep_addr)
+    if (audio->ep_int == ep_addr)
     {
       // According to USB2 specification, maximum payload of interrupt EP is 8 bytes on low speed, 64 bytes on full speed, and 1024 bytes on high speed (but only if an alternate interface other than 0 is used - see specification p. 49)
       // In case there is nothing to send we have to return a NAK - this is taken care of by PHY ???
@@ -2132,7 +2151,8 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
       // I assume here, that things above are handled by PHY
       // All transmission is done - what remains to do is to inform job was completed
 
-      if (tud_audio_int_ctr_done_cb) TU_VERIFY(tud_audio_int_ctr_done_cb(rhport, (uint16_t) xferred_bytes));
+      if (tud_audio_int_done_cb) tud_audio_int_done_cb(rhport);
+      return true;
     }
 
 #endif