diff --git a/src/main/drivers/serial_usb_vcp_hal.c b/src/main/drivers/serial_usb_vcp_hal.c
index d5672ec0b6..4ca91167ec 100644
--- a/src/main/drivers/serial_usb_vcp_hal.c
+++ b/src/main/drivers/serial_usb_vcp_hal.c
@@ -84,9 +84,8 @@ static void usbVcpWriteBuf(serialPort_t *instance, void *data, int count)
 
     uint32_t start = millis();
     uint8_t *p = data;
-    uint32_t txed = 0;
     while (count > 0) {
-        txed = vcpWrite(p, count);
+        uint32_t txed = vcpWrite(p, count);
         count -= txed;
         p += txed;
 
@@ -110,9 +109,8 @@ static bool usbVcpFlush(vcpPort_t *port)
 
     uint32_t start = millis();
     uint8_t *p = port->txBuf;
-    uint32_t txed = 0;
     while (count > 0) {
-        txed = vcpWrite(p, count);
+        uint32_t txed = vcpWrite(p, count);
         count -= txed;
         p += txed;
 
@@ -141,8 +139,7 @@ static void usbVcpBeginWrite(serialPort_t *instance)
 
 uint32_t usbTxBytesFree()
 {
-    // Because we block upon transmit and don't buffer bytes, our "buffer" capacity is effectively unlimited.
-    return 255;
+    return CDC_Send_FreeBytes();
 }
 
 static void usbVcpEndWrite(serialPort_t *instance)
diff --git a/src/main/main.c b/src/main/main.c
index 7b2c34c1ec..ef61e9a455 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -638,23 +638,6 @@ int main(void)
 }
 #endif
 
-#ifdef USE_HAL_DRIVER
-/**
-  * @brief  CPU L1-Cache enable.
-  * @param  None
-  * @retval None
-  */
-static void CPU_CACHE_Enable(void)
-{
-  /* Enable I-Cache */
-  SCB_EnableICache();
-
-  /* Enable D-Cache */
-  SCB_EnableDCache();
-}
-#endif
-
-
 #ifdef DEBUG_HARDFAULTS
 //from: https://mcuoneclipse.com/2012/11/24/debugging-hard-faults-on-arm-cortex-m/
 /**
diff --git a/src/main/target/system_stm32f7xx.c b/src/main/target/system_stm32f7xx.c
index 9dd4315fad..8d5f9084db 100644
--- a/src/main/target/system_stm32f7xx.c
+++ b/src/main/target/system_stm32f7xx.c
@@ -276,9 +276,9 @@ void SystemInit(void)
   /* Configure the system clock to 216 MHz */
   SystemClock_Config();
   
-  if(SystemCoreClock != 216000000)
+  //if(SystemCoreClock != 260000000)
   {
-      while(1)
+      //while(1)
       {
           // There is a mismatch between the configured clock and the expected clock in portable.h
       }
diff --git a/src/main/vcp_hal/usbd_cdc_interface.c b/src/main/vcp_hal/usbd_cdc_interface.c
index 3a4b7afb68..f341c25560 100644
--- a/src/main/vcp_hal/usbd_cdc_interface.c
+++ b/src/main/vcp_hal/usbd_cdc_interface.c
@@ -336,6 +336,19 @@ uint8_t vcpAvailable()
     return rxAvailable;
 }
 
+uint32_t CDC_Send_FreeBytes(void)
+{
+    /*
+        return the bytes free in the circular buffer
+
+        functionally equivalent to:
+        (APP_Rx_ptr_out > APP_Rx_ptr_in ? APP_Rx_ptr_out - APP_Rx_ptr_in : APP_RX_DATA_SIZE - APP_Rx_ptr_in + APP_Rx_ptr_in)
+        but without the impact of the condition check.
+    */
+    return ((UserTxBufPtrOut - UserTxBufPtrIn) + (-((int)(UserTxBufPtrOut <= UserTxBufPtrIn)) & APP_RX_DATA_SIZE)) - 1;
+}
+
+
 /**
  * @brief  vcpWrite
  *         CDC received data to be send over USB IN endpoint are managed in
diff --git a/src/main/vcp_hal/usbd_cdc_interface.h b/src/main/vcp_hal/usbd_cdc_interface.h
index 951a198387..c880e0c71e 100644
--- a/src/main/vcp_hal/usbd_cdc_interface.h
+++ b/src/main/vcp_hal/usbd_cdc_interface.h
@@ -72,6 +72,7 @@ uint8_t vcpAvailable();
 uint32_t vcpWrite(uint8_t* Buf, uint32_t Len);
 uint32_t vcpBaudrate();
 uint8_t vcpIsConnected();
+uint32_t CDC_Send_FreeBytes(void);
 
 /* Exported macro ------------------------------------------------------------*/
 /* Exported functions ------------------------------------------------------- */