3 files changed, 8 insertions, 1 deletions
diff --git a/supervisor/serial.h b/supervisor/serial.h
index 066886303..9c2d44737 100644
--- a/supervisor/serial.h
+++ b/supervisor/serial.h
@@ -47,4 +47,5 @@ char serial_read(void);
 bool serial_bytes_available(void);
 bool serial_connected(void);
 
+extern volatile bool _serial_connected;
 #endif  // MICROPY_INCLUDED_SUPERVISOR_SERIAL_H
diff --git a/supervisor/shared/serial.c b/supervisor/shared/serial.c
index 303f89e75..91e90671d 100644
--- a/supervisor/shared/serial.c
+++ b/supervisor/shared/serial.c
@@ -47,6 +47,8 @@ busio_uart_obj_t debug_uart;
 byte buf_array[64];
 #endif
 
+volatile bool _serial_connected;
+
 void serial_early_init(void) {
 #if defined(DEBUG_UART_TX) && defined(DEBUG_UART_RX)
     debug_uart.base.type = &busio_uart_type;
@@ -69,7 +71,7 @@ bool serial_connected(void) {
 #if defined(DEBUG_UART_TX) && defined(DEBUG_UART_RX)
     return true;
 #else
-    return tud_cdc_connected();
+    return _serial_connected;
 #endif
 }
 
diff --git a/supervisor/shared/usb/usb.c b/supervisor/shared/usb/usb.c
index e8541669a..89fbf56f3 100644
--- a/supervisor/shared/usb/usb.c
+++ b/supervisor/shared/usb/usb.c
@@ -29,6 +29,7 @@
 #include "shared-module/usb_midi/__init__.h"
 #include "supervisor/background_callback.h"
 #include "supervisor/port.h"
+#include "supervisor/serial.h"
 #include "supervisor/usb.h"
 #include "lib/utils/interrupt_char.h"
 #include "lib/mp-readline/readline.h"
@@ -115,6 +116,7 @@ void tud_umount_cb(void) {
 // remote_wakeup_en : if host allows us to perform remote wakeup
 // USB Specs: Within 7ms, device must draw an average current less than 2.5 mA from bus
 void tud_suspend_cb(bool remote_wakeup_en) {
+    _serial_connected = false;
 }
 
 // Invoked when usb bus is resumed
@@ -126,6 +128,8 @@ void tud_resume_cb(void) {
 void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts) {
     (void) itf; // interface ID, not used
 
+    _serial_connected = dtr;
+
     // DTR = false is counted as disconnected
     if ( !dtr )
     {