From 3fbd0b1a3bf6e3aa7984101b7dcbebf9f76b00cd Mon Sep 17 00:00:00 2001
From: Venelin Efremov <ghent360@iqury.us>
Date: Mon, 25 Mar 2019 00:42:12 -0700
Subject: [PATCH] Fix issue #478.

---
 cores/arduino/stm32/usb/cdc/usbd_cdc_if.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/cores/arduino/stm32/usb/cdc/usbd_cdc_if.c b/cores/arduino/stm32/usb/cdc/usbd_cdc_if.c
index 54c0360eeb..bdc342594d 100644
--- a/cores/arduino/stm32/usb/cdc/usbd_cdc_if.c
+++ b/cores/arduino/stm32/usb/cdc/usbd_cdc_if.c
@@ -263,8 +263,9 @@ void CDC_deInit(void)
 
 bool CDC_connected()
 {
-  uint32_t transmitTime = 0;
-  if (transmitStart) {
+  // Save the transmitStart value in a local variable - fix #478
+  uint32_t transmitTime = transmitStart;
+  if (transmitTime) {
     transmitTime = HAL_GetTick() - transmitStart;
   }
   return hUSBD_Device_CDC.dev_state == USBD_STATE_CONFIGURED