diff --git a/.gitignore b/.gitignore
index e6ccec736e..56ae7600f1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -57,6 +57,7 @@ hw/mcu/st/cmsis_device_f4
 hw/mcu/st/cmsis_device_f7
 hw/mcu/st/cmsis_device_g0
 hw/mcu/st/cmsis_device_g4
+hw/mcu/st/cmsis_device_h5
 hw/mcu/st/cmsis_device_h7
 hw/mcu/st/cmsis_device_l0
 hw/mcu/st/cmsis_device_l1
@@ -72,6 +73,7 @@ hw/mcu/st/stm32f4xx_hal_driver
 hw/mcu/st/stm32f7xx_hal_driver
 hw/mcu/st/stm32g0xx_hal_driver
 hw/mcu/st/stm32g4xx_hal_driver
+hw/mcu/st/stm32h5xx_hal_driver
 hw/mcu/st/stm32h7xx_hal_driver
 hw/mcu/st/stm32l0xx_hal_driver
 hw/mcu/st/stm32l1xx_hal_driver
diff --git a/src/class/usbtmc/usbtmc.h b/src/class/usbtmc/usbtmc.h
index 090ab3c4ab..327de087c7 100644
--- a/src/class/usbtmc/usbtmc.h
+++ b/src/class/usbtmc/usbtmc.h
@@ -183,6 +183,23 @@ typedef enum {
 
 } usmtmc_request_type_enum;
 
+typedef enum {
+  // The last and first valid bNotify1 for use by the USBTMC class specification.
+  USBTMC_bNOTIFY1_USBTMC_FIRST          = 0x00,
+  USBTMC_bNOTIFY1_USBTMC_LAST           = 0x3F,
+
+  // The last and first valid bNotify1 for use by vendors.
+  USBTMC_bNOTIFY1_VENDOR_SPECIFIC_FIRST = 0x40,
+  USBTMC_bNOTIFY1_VENDOR_SPECIFIC_LAST  = 0x7F,
+
+  // The last and first valid bNotify1 for use by USBTMC subclass specifications.
+  USBTMC_bNOTIFY1_SUBCLASS_FIRST        = 0x80,
+  USBTMC_bNOTIFY1_SUBCLASS_LAST         = 0xFF,
+
+  // From the USB488 Subclass Specification, Section 3.4.
+  USB488_bNOTIFY1_SRQ                   = 0x81,
+} usbtmc_int_in_payload_format;
+
 typedef enum {
   USBTMC_STATUS_SUCCESS = 0x01,
   USBTMC_STATUS_PENDING = 0x02,
@@ -303,6 +320,14 @@ typedef struct TU_ATTR_PACKED
 
 TU_VERIFY_STATIC(sizeof(usbtmc_read_stb_rsp_488_t) == 3u, "struct wrong length");
 
+typedef struct TU_ATTR_PACKED
+{
+  uint8_t bNotify1; // Must be USB488_bNOTIFY1_SRQ
+  uint8_t StatusByte;
+} usbtmc_srq_interrupt_488_t;
+
+TU_VERIFY_STATIC(sizeof(usbtmc_srq_interrupt_488_t) == 2u, "struct wrong length");
+
 typedef struct TU_ATTR_PACKED
 {
   struct TU_ATTR_PACKED
diff --git a/src/class/usbtmc/usbtmc_device.c b/src/class/usbtmc/usbtmc_device.c
index 573654d58b..f80abdaf33 100644
--- a/src/class/usbtmc/usbtmc_device.c
+++ b/src/class/usbtmc/usbtmc_device.c
@@ -86,6 +86,11 @@ tu_static char logMsg[150];
 // imposes a minimum buffer size of 32 bytes.
 #define USBTMCD_BUFFER_SIZE (TUD_OPT_HIGH_SPEED ? 512 : 64)
 
+// Interrupt endpoint buffer size, default to 2 bytes as USB488 specification.
+#ifndef CFG_TUD_USBTMC_INT_EP_SIZE
+#define CFG_TUD_USBTMC_INT_EP_SIZE 2
+#endif
+
 /*
  * The state machine does not allow simultaneous reading and writing. This is
  * consistent with USBTMC.
@@ -124,13 +129,15 @@ typedef struct
   uint8_t ep_bulk_in;
   uint8_t ep_bulk_out;
   uint8_t ep_int_in;
+  uint32_t ep_bulk_in_wMaxPacketSize;
+  uint32_t ep_bulk_out_wMaxPacketSize;
   // IN buffer is only used for first packet, not the remainder
   // in order to deal with prepending header
   CFG_TUSB_MEM_ALIGN uint8_t ep_bulk_in_buf[USBTMCD_BUFFER_SIZE];
-  uint32_t ep_bulk_in_wMaxPacketSize;
   // OUT buffer receives one packet at a time
   CFG_TUSB_MEM_ALIGN uint8_t ep_bulk_out_buf[USBTMCD_BUFFER_SIZE];
-  uint32_t ep_bulk_out_wMaxPacketSize;
+  // Buffer int msg to ensure alignment and placement correctness
+  CFG_TUSB_MEM_ALIGN uint8_t ep_int_in_buf[CFG_TUD_USBTMC_INT_EP_SIZE];
 
   uint32_t transfer_size_remaining; // also used for requested length for bulk IN.
   uint32_t transfer_size_sent;      // To keep track of data bytes that have been queued in FIFO (not header bytes)
@@ -240,6 +247,19 @@ bool tud_usbtmc_transmit_dev_msg_data(
   return true;
 }
 
+bool tud_usbtmc_transmit_notification_data(const void * data, size_t len)
+{
+#ifndef NDEBUG
+  TU_ASSERT(len > 0);
+  TU_ASSERT(usbtmc_state.ep_int_in != 0);
+#endif
+  TU_VERIFY(usbd_edpt_busy(usbtmc_state.rhport, usbtmc_state.ep_int_in));
+
+  TU_VERIFY(tu_memcpy_s(usbtmc_state.ep_int_in_buf, sizeof(usbtmc_state.ep_int_in_buf), data, len) == 0);
+  TU_VERIFY(usbd_edpt_xfer(usbtmc_state.rhport, usbtmc_state.ep_int_in, usbtmc_state.ep_int_in_buf, (uint16_t)len));
+  return true;
+}
+
 void usbtmcd_init_cb(void)
 {
   usbtmc_state.capabilities = tud_usbtmc_get_capabilities_cb();
@@ -540,9 +560,10 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
     case STATE_TX_INITIATED:
       if(usbtmc_state.transfer_size_remaining >= sizeof(usbtmc_state.ep_bulk_in_buf))
       {
-        // FIXME! This removes const below!
+        // Copy buffer to ensure alignment correctness
+        memcpy(usbtmc_state.ep_bulk_in_buf, usbtmc_state.devInBuffer, sizeof(usbtmc_state.ep_bulk_in_buf));
         TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_in,
-            (void*)(uintptr_t) usbtmc_state.devInBuffer, sizeof(usbtmc_state.ep_bulk_in_buf)));
+            usbtmc_state.ep_bulk_in_buf, sizeof(usbtmc_state.ep_bulk_in_buf)));
         usbtmc_state.devInBuffer += sizeof(usbtmc_state.ep_bulk_in_buf);
         usbtmc_state.transfer_size_remaining -= sizeof(usbtmc_state.ep_bulk_in_buf);
         usbtmc_state.transfer_size_sent += sizeof(usbtmc_state.ep_bulk_in_buf);
@@ -578,7 +599,9 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
     }
   }
   else if (ep_addr == usbtmc_state.ep_int_in) {
-    // Good?
+    if (tud_usbtmc_notification_complete_cb) {
+      TU_VERIFY(tud_usbtmc_notification_complete_cb());
+    }
     return true;
   }
   return false;
diff --git a/src/class/usbtmc/usbtmc_device.h b/src/class/usbtmc/usbtmc_device.h
index c1298ddb88..af7ea6ec9a 100644
--- a/src/class/usbtmc/usbtmc_device.h
+++ b/src/class/usbtmc/usbtmc_device.h
@@ -73,6 +73,10 @@ bool tud_usbtmc_check_abort_bulk_in_cb(usbtmc_check_abort_bulk_rsp_t *rsp);
 bool tud_usbtmc_check_abort_bulk_out_cb(usbtmc_check_abort_bulk_rsp_t *rsp);
 bool tud_usbtmc_check_clear_cb(usbtmc_get_clear_status_rsp_t *rsp);
 
+// The interrupt-IN endpoint buffer was transmitted to the host. Use
+// tud_usbtmc_transmit_notification_data to send another notification.
+TU_ATTR_WEAK bool tud_usbtmc_notification_complete_cb(void);
+
 // Indicator pulse should be 0.5 to 1.0 seconds long
 TU_ATTR_WEAK bool tud_usbtmc_indicator_pulse_cb(tusb_control_request_t const * msg, uint8_t *tmcResult);
 
@@ -82,17 +86,23 @@ TU_ATTR_WEAK bool tud_usbtmc_msg_trigger_cb(usbtmc_msg_generic_t* msg);
 //TU_ATTR_WEAK bool tud_usbtmc_app_go_to_local_cb();
 #endif
 
-/*******************************************
- * Called from app
- *
- * We keep a reference to the buffer, so it MUST not change until the app is
- * notified that the transfer is complete.
- ******************************************/
-
+// Called from app
+//
+// We keep a reference to the buffer, so it MUST not change until the app is
+// notified that the transfer is complete.
 bool tud_usbtmc_transmit_dev_msg_data(
     const void * data, size_t len,
     bool endOfMessage, bool usingTermChar);
 
+// Buffers a notification to be sent to the host. The data starts
+// with the bNotify1 field, see the USBTMC Specification, Table 13.
+//
+// If the previous notification data has not yet been sent, this
+// returns false.
+//
+// Requires an interrupt endpoint in the interface.
+bool tud_usbtmc_transmit_notification_data(const void * data, size_t len);
+
 bool tud_usbtmc_start_bus_read(void);
 
 
@@ -104,9 +114,4 @@ bool     usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result,
 bool     usbtmcd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request);
 void     usbtmcd_init_cb(void);
 
-/************************************************************
- * USBTMC Descriptor Templates
- *************************************************************/
-
-
 #endif /* CLASS_USBTMC_USBTMC_DEVICE_H_ */