- X7S option removed (#5388)

- runtime detection of bluetooth chip

radio/src/targets/common/arm/stm32/bluetooth_driver.cpp

@@ -2,7 +2,7 @@
  * Copyright (C) OpenTX
  *
  * Based on code named
- *   th9x - http://code.google.com/p/th9x 
+ *   th9x - http://code.google.com/p/th9x
  *   er9x - http://code.google.com/p/er9x
  *   gruvin9x - http://code.google.com/p/gruvin9x
  *
@@ -23,6 +23,10 @@
 Fifo<uint8_t, 64> btTxFifo;
 Fifo<uint8_t, 64> btRxFifo;
 
+#if defined(PCBX7)
+uint8_t btChipPresent = 0;
+#endif
+
 enum BluetoothWriteState
 {
   BLUETOOTH_WRITE_IDLE,
@@ -105,6 +109,12 @@ extern "C" void BT_USART_IRQHandler(void)
     USART_ClearITPendingBit(BT_USART, USART_IT_RXNE);
     uint8_t byte = USART_ReceiveData(BT_USART);
     btRxFifo.push(byte);
+#if defined(PCBX7)
+    if (!btChipPresent) {   //This is to differentiate X7 and X7S
+      btChipPresent = 1;
+      bluetoothDone();
+    }
+#endif
   }
 
   if (USART_GetITStatus(BT_USART, USART_IT_TXE) != RESET) {