Previous changes to USB connection state management to fix behavior on Windows was broken. This appears to work on Windows, Linux and MacOS.

Src/usbd_cdc_if.c

@@ -55,7 +55,7 @@
 #include "UsbPort.h"
 #include "main.h"
 #include "cmsis_os.h"
-extern osMessageQId ioEventQueueHandle;
+#include "IOEventTask.h"
 
 /* USER CODE END INCLUDE */
 
@@ -65,7 +65,6 @@ extern osMessageQId ioEventQueueHandle;
 
 /* USER CODE BEGIN PV */
 /* Private variables ---------------------------------------------------------*/
-static int connected = 0;
 /* USER CODE END PV */
 
 /** @addtogroup STM32_USB_OTG_DEVICE_LIBRARY
@@ -262,10 +261,6 @@ static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length)
   /* 6      | bDataBits  |   1   | Number Data bits (5, 6, 7, 8 or 16).          */
   /*******************************************************************************/
     case CDC_SET_LINE_CODING:
-        if (!connected) {
-            connected = 1;
-            osMessagePut(ioEventQueueHandle, CMD_USB_CDC_CONNECT, 0);
-        }
         LineCoding.bitrate    = (uint32_t)(pbuf[0] | (pbuf[1] << 8) | (pbuf[2] << 16) | (pbuf[3] << 24));
         LineCoding.format     = pbuf[4];
         LineCoding.paritytype = pbuf[5];
@@ -285,11 +280,9 @@ static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length)
     case CDC_SET_CONTROL_LINE_STATE:
         if (length == 0) {
           USBD_SetupReqTypedef* req = (USBD_SetupReqTypedef*) pbuf;
-          if ((req->wValue & 1) && (!connected)) {
+          if ((req->wValue & 1)) {
-            connected = 1;
             osMessagePut(ioEventQueueHandle, CMD_USB_CDC_CONNECT, 0);
-          } else if (connected) {
+          } else {
-            connected = 0;
             osMessagePut(ioEventQueueHandle, CMD_USB_CDC_DISCONNECT, 0);
           }
         }
@@ -313,7 +306,7 @@ static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length)
   *
   *         @note
   *         This function will block any OUT packet reception on USB endpoint
-  *         untill exiting this function. If you exit this function before transfer
+  *         until exiting this function. If you exit this function before transfer
   *         is complete on CDC interface (ie. using DMA controller) it will result
   *         in receiving more data while previous ones are still not sent.
   *
@@ -324,8 +317,7 @@ static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length)
 static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len)
 {
   /* USER CODE BEGIN 6 */
-    if (!connected) {
+    if (!cdc_connected) {
-        connected = 1;
         osMessagePut(ioEventQueueHandle, CMD_USB_CDC_CONNECT, 0);
     }
   cdc_receive(Buf, *Len);

TNC/IOEventTask.cpp

@@ -32,6 +32,8 @@ extern "C" void stop2(void);
 extern "C" void shutdown(void const * argument);
 extern "C" void startLedBlinkerTask(void const*);
 
+volatile int cdc_connected{0};
+
 static PTT getPttStyle(const mobilinkd::tnc::kiss::Hardware& hardware)
 {
     return hardware.options & KISS_OPTION_PTT_SIMPLEX ? PTT::SIMPLEX : PTT::MULTIPLEX;
@@ -123,8 +125,9 @@ void startIOEventTask(void const*)
         {
             switch (cmd) {
             case CMD_USB_CDC_CONNECT:
-                if (openCDC())
+                if (!cdc_connected && openCDC())
                 {
+                    cdc_connected = true;
                     // Disable Bluetooth Module
                     HAL_NVIC_DisableIRQ(EXTI4_IRQn);
                     HAL_NVIC_DisableIRQ(EXTI9_5_IRQn);
@@ -152,21 +155,24 @@ void startIOEventTask(void const*)
                 }
             [[ fallthrough ]]; // when the CDC part was connected.
             case CMD_USB_CDC_DISCONNECT:
-                osMessagePut(audioInputQueueHandle, audio::IDLE,
+                if (cdc_connected) {
-                    osWaitForever);
+                    cdc_connected = false;
-                kiss::getAFSKTestTone().stop();
+                    osMessagePut(audioInputQueueHandle, audio::IDLE,
-                closeCDC();
+                        osWaitForever);
-                INFO("CDC Closed");
+                    kiss::getAFSKTestTone().stop();
+                    closeCDC();
+                    INFO("CDC Closed");
 
-                // Enable Bluetooth Module
+                    // Enable Bluetooth Module
-                HAL_GPIO_WritePin(BT_SLEEP_GPIO_Port, BT_SLEEP_Pin,
+                    HAL_GPIO_WritePin(BT_SLEEP_GPIO_Port, BT_SLEEP_Pin,
-                    GPIO_PIN_SET);
+                        GPIO_PIN_SET);
-                bm78_wait_until_ready();
+                    bm78_wait_until_ready();
 
-                HAL_NVIC_EnableIRQ(EXTI4_IRQn);
+                    HAL_NVIC_EnableIRQ(EXTI4_IRQn);
-                HAL_NVIC_EnableIRQ(EXTI9_5_IRQn);
+                    HAL_NVIC_EnableIRQ(EXTI9_5_IRQn);
 
-                indicate_waiting_to_connect();
+                    indicate_waiting_to_connect();
+                }
                 break;
             case CMD_POWER_BUTTON_DOWN:
                 INFO("Power Down");

TNC/IOEventTask.h

@@ -13,11 +13,12 @@ extern "C" {
 void startIOEventTask(void const* argument);
 void startCdcBlinker(void const* argument);
 
+extern osMessageQId ioEventQueueHandle;
+extern volatile int cdc_connected;
+
 #ifdef __cplusplus
 }
 
-extern osMessageQId ioEventQueueHandle;
-
 namespace mobilinkd { namespace tnc {
 
 void print_startup_banner() __attribute__((noinline));