add Uart _begun, fix potetial hard fault with Debug level ON but Serial.begin() is not called

Author: hathach

cores/nRF5/Uart.cpp

@@ -28,6 +28,8 @@ Uart::Uart(NRF_UART_Type *_nrfUart, IRQn_Type _IRQn, uint8_t _pinRX, uint8_t _pi
   uc_pinRX = g_ADigitalPinMap[_pinRX];
   uc_pinTX = g_ADigitalPinMap[_pinTX];
   uc_hwFlow = 0;
+
+  _begun = false;
 }
 
 Uart::Uart(NRF_UART_Type *_nrfUart, IRQn_Type _IRQn, uint8_t _pinRX, uint8_t _pinTX, uint8_t _pinCTS, uint8_t _pinRTS)
@@ -39,6 +41,8 @@ Uart::Uart(NRF_UART_Type *_nrfUart, IRQn_Type _IRQn, uint8_t _pinRX, uint8_t _pi
   uc_pinCTS = g_ADigitalPinMap[_pinCTS];
   uc_pinRTS = g_ADigitalPinMap[_pinRTS];
   uc_hwFlow = 1;
+
+  _begun = false;
 }
 
 void Uart::begin(unsigned long baudrate)
@@ -147,6 +151,8 @@ void Uart::begin(unsigned long baudrate, uint16_t /*config*/)
   NVIC_ClearPendingIRQ(IRQn);
   NVIC_SetPriority(IRQn, 3);
   NVIC_EnableIRQ(IRQn);
+
+  _begun = true;
 }
 
 void Uart::end()

cores/nRF5/Uart.h

@@ -43,7 +43,7 @@ class Uart : public HardwareSerial
 
     void IrqHandler();
 
-    operator bool() { return true; }
+    operator bool() { return _begun; }
 
   private:
     NRF_UART_Type *nrfUart;
@@ -56,6 +56,8 @@ class Uart : public HardwareSerial
     uint8_t uc_pinCTS;
     uint8_t uc_pinRTS;
     uint8_t uc_hwFlow;
+
+    bool _begun;
 };
 
 #ifdef __cplusplus

cores/nRF5/main.cpp

@@ -34,6 +34,8 @@ static void loop_task(void* arg)
   setup();
 
 #if CFG_DEBUG
+  // If Serial is not begin(), call it to avoid hard fault
+  if (!Serial) Serial.begin(115200);
   dbgPrintVersion();
 #endif