From 0322ef071cfae8dd20058c81359b01924b5e569e Mon Sep 17 00:00:00 2001
From: Oskar Weigl <oskar.weigl@gmail.com>
Date: Wed, 11 Oct 2017 00:13:33 -0700
Subject: [PATCH] check for usb busy

---
 Src/syscalls.c    | 1 -
 Src/usbd_cdc_if.c | 5 ++++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Src/syscalls.c b/Src/syscalls.c
index e58a4420..3cd2a073 100644
--- a/Src/syscalls.c
+++ b/Src/syscalls.c
@@ -36,7 +36,6 @@ int _write(int file, char *data, int len) {
       if (len > UART_TX_BUFFER_SIZE)
         return 0;
       // Check if transfer is already ongoing
-      // TODO: use HAL_UART_GetState
       if(huart4.gState != HAL_UART_STATE_READY)
         return 0;
       // memcpy data into uart_tx_buf
diff --git a/Src/usbd_cdc_if.c b/Src/usbd_cdc_if.c
index 57680540..e3882cce 100644
--- a/Src/usbd_cdc_if.c
+++ b/Src/usbd_cdc_if.c
@@ -300,7 +300,10 @@ uint8_t CDC_Transmit_FS(uint8_t* Buf, uint16_t Len)
   //Check length
   if (Len > APP_TX_DATA_SIZE)
     return USBD_FAIL;
-  // TODO: check busy
+  // Check for ongoing transmission
+  USBD_CDC_HandleTypeDef* hcdc = (USBD_CDC_HandleTypeDef*) hUsbDeviceFS.pClassData;
+  if (hcdc->TxState != 0)
+    return USBD_BUSY;
   // memcpy Buf into UserTxBufferFS
   memcpy(UserTxBufferFS, Buf, Len);
   // Update Len