diff --git a/extmod/machine_usb_device.c b/extmod/machine_usb_device.c
index f6e97f42054d1..e8303ef84f769 100644
--- a/extmod/machine_usb_device.c
+++ b/extmod/machine_usb_device.c
@@ -28,7 +28,7 @@
 
 #if MICROPY_HW_ENABLE_USB_RUNTIME_DEVICE
 
-#include "mp_usbd.h"
+#include "shared/tinyusb/mp_usbd.h"
 #include "py/mperrno.h"
 #include "py/objstr.h"
 
diff --git a/ports/stm32/Makefile b/ports/stm32/Makefile
index 63ed974b9b551..7597d23d0a3e9 100644
--- a/ports/stm32/Makefile
+++ b/ports/stm32/Makefile
@@ -111,7 +111,7 @@ INC += -I$(STM32LIB_HAL_ABS)/Inc
 INC += -I$(USBDEV_DIR)/core/inc -I$(USBDEV_DIR)/class/inc
 #INC += -I$(USBHOST_DIR)
 INC += -I$(TOP)/lib/tinyusb/src
-INC += -I$(TOP)/shared/tinyusb/
+INC += -Itinyusb_port
 INC += -Ilwip_inc
 
 CFLAGS += $(INC) -Wall -Wpointer-arith -Werror -Wdouble-promotion -Wfloat-conversion -std=gnu99 $(CFLAGS_EXTRA)
diff --git a/ports/stm32/factoryreset.c b/ports/stm32/factoryreset.c
index 50854a908b18e..1811ca1186f3f 100644
--- a/ports/stm32/factoryreset.c
+++ b/ports/stm32/factoryreset.c
@@ -44,9 +44,15 @@ static const char fresh_boot_py[] =
     "import pyb\r\n"
     "#pyb.main('main.py') # main script to run after this one\r\n"
 #if MICROPY_HW_ENABLE_USB
+#if MICROPY_HW_TINYUSB_STACK
+    "#usb = machine.USBDevice()\r\n"
+    "#usb.builtin_driver = machine.USBDevice.BUILTIN_DEFAULT  # CDC + MSC\r\n"
+    "#usb.active(True)\r\n"
+#else
     "#pyb.usb_mode('VCP+MSC') # act as a serial and a storage device\r\n"
     "#pyb.usb_mode('VCP+HID') # act as a serial device and a mouse\r\n"
 #endif
+#endif
 #if MICROPY_PY_NETWORK
     "#import network\r\n"
     "#network.country('US') # ISO 3166-1 Alpha-2 code, eg US, GB, DE, AU or XX for worldwide\r\n"
diff --git a/ports/stm32/stm32_it.c b/ports/stm32/stm32_it.c
index 3ae1980f8feb7..f528314a5e096 100644
--- a/ports/stm32/stm32_it.c
+++ b/ports/stm32/stm32_it.c
@@ -384,7 +384,7 @@ void USB1_OTG_HS_IRQHandler(void) {
 void OTG_HS_IRQHandler(void) {
     IRQ_ENTER(OTG_HS_IRQn);
     #if MICROPY_HW_TINYUSB_STACK
-    tud_int_handler(0);
+    tud_int_handler(1); // OTG_HS is always RHPORT1 on F4/F7/H7 (not N6, which uses USB1_OTG_HS_IRQHandler)
     #else
     HAL_PCD_IRQHandler(&pcd_hs_handle);
     #endif
diff --git a/ports/stm32/tinyusb_port/tusb_config.h b/ports/stm32/tinyusb_port/tusb_config.h
new file mode 100644
index 0000000000000..4d74eec9b37b5
--- /dev/null
+++ b/ports/stm32/tinyusb_port/tusb_config.h
@@ -0,0 +1,51 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2026 Andrew Leech
+ *
+ * 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 MICROPY_INCLUDED_STM32_TINYUSB_PORT_TUSB_CONFIG_H
+#define MICROPY_INCLUDED_STM32_TINYUSB_PORT_TUSB_CONFIG_H
+
+#include "py/mpconfig.h"
+
+// STM32F4/F7/H7 boards with USB_HS use OTG_HS on RHPORT1, not RHPORT0.
+// Disable RHPORT0 and put RHPORT1 in device mode (HS, or FS when the
+// HS controller uses the internal FS PHY via MICROPY_HW_USB_HS_IN_FS).
+// Other configs are handled either by the board (e.g. N6 sets RHPORT0
+// to HS in mpconfigboard_common.h) or by the shared default in
+// shared/tinyusb/tusb_config.h (RHPORT0 in FS device mode).
+
+// These families place OTG_HS on RHPORT1. Extend the list if a new family
+// also uses OTG_HS on RHPORT1 rather than RHPORT0.
+#if MICROPY_HW_USB_HS && (defined(STM32F4) || defined(STM32F7) || defined(STM32H7))
+#define CFG_TUSB_RHPORT0_MODE (OPT_MODE_NONE)
+#if MICROPY_HW_USB_HS_IN_FS
+#define CFG_TUSB_RHPORT1_MODE (OPT_MODE_DEVICE | OPT_MODE_FULL_SPEED)
+#else
+#define CFG_TUSB_RHPORT1_MODE (OPT_MODE_DEVICE | OPT_MODE_HIGH_SPEED)
+#endif
+#endif
+
+#include "shared/tinyusb/tusb_config.h"
+
+#endif // MICROPY_INCLUDED_STM32_TINYUSB_PORT_TUSB_CONFIG_H
diff --git a/ports/stm32/usbd.c b/ports/stm32/usbd.c
index 35275cd1bd02e..d8f8b3dd551c8 100644
--- a/ports/stm32/usbd.c
+++ b/ports/stm32/usbd.c
@@ -28,15 +28,25 @@
 
 #if MICROPY_HW_ENABLE_USBDEV && MICROPY_HW_TINYUSB_STACK
 
-#include "mp_usbd.h"
-#include "py/mpconfig.h"
-#include "string.h"
+#include <string.h>
+#include "shared/tinyusb/mp_usbd.h"
 #include "mphalport.h"
 
 void mp_usbd_port_get_serial_number(char *serial_buf) {
+    // Use the same algorithm as the ST DFU bootloader so that the serial
+    // number is consistent across all USB modes.
+    MP_STATIC_ASSERT(12 <= MICROPY_HW_USB_DESC_STR_MAX); // 6 derived bytes x 2 hex digits + NUL
+    static const char hexdig[] = "0123456789ABCDEF";
     uint8_t *id = (uint8_t *)MP_HAL_UNIQUE_ID_ADDRESS;
-    MP_STATIC_ASSERT(12 * 2 <= MICROPY_HW_USB_DESC_STR_MAX);
-    mp_usbd_hex_str(serial_buf, id, 12);
+    uint8_t bytes[] = {
+        id[11], (uint8_t)(id[10] + id[2]), id[9],
+        (uint8_t)(id[8] + id[0]), id[7], id[6],
+    };
+    for (int i = 0; i < 6; i++) {
+        serial_buf[i * 2] = hexdig[bytes[i] >> 4];
+        serial_buf[i * 2 + 1] = hexdig[bytes[i] & 0x0f];
+    }
+    serial_buf[12] = '\0';
 }
 
 #endif
diff --git a/shared/tinyusb/mp_usbd_cdc.c b/shared/tinyusb/mp_usbd_cdc.c
index 961bdf89896ff..8018032d36cbc 100644
--- a/shared/tinyusb/mp_usbd_cdc.c
+++ b/shared/tinyusb/mp_usbd_cdc.c
@@ -34,6 +34,11 @@
 
 #if MICROPY_HW_USB_CDC && MICROPY_HW_ENABLE_USBDEV && !MICROPY_EXCLUDE_SHARED_TINYUSB_USBD_CDC
 
+// TinyUSB has no public API for endpoint stall detection/clearing; this
+// private header is the intended interface for class drivers (all built-in
+// TinyUSB class drivers include it for the same purpose).
+#include "device/usbd_pvt.h"
+
 static uint8_t cdc_itf_pending; // keep track of cdc interfaces which need attention to poll
 static int8_t cdc_connected_flush_delay = 0;
 
@@ -176,10 +181,18 @@ void MICROPY_WRAP_TUD_CDC_LINE_STATE_CB(tud_cdc_line_state_cb)(uint8_t itf, bool
     #if MICROPY_HW_USB_CDC && !MICROPY_EXCLUDE_SHARED_TINYUSB_USBD_CDC
     if (dtr) {
         // A host application has started to open the cdc serial port.
+        // USBD_CDC_EP_IN is the IN endpoint for itf 0; only clear stall for itf 0.
+        if (itf == 0 && usbd_edpt_stalled(TUD_OPT_RHPORT, USBD_CDC_EP_IN)) {
+            usbd_edpt_clear_stall(TUD_OPT_RHPORT, USBD_CDC_EP_IN);
+        }
         // Wait a few ms for host to be ready then send tx buffer.
         // High speed connection SOF fires at 125us, full speed at 1ms.
         cdc_connected_flush_delay = (tud_speed_get() == TUSB_SPEED_HIGH) ? 128 : 16;
         tud_sof_cb_enable(true);
+    } else {
+        // Host has closed the cdc serial port. Discard pending TX data to
+        // avoid a full FIFO blocking writes on the next connection.
+        tud_cdc_n_write_clear(itf);
     }
     #endif
     #if MICROPY_HW_USB_CDC_DTR_RTS_BOOTLOADER