[libs] Allow setting UART pin numbers in Serial.begin()

Author: kuba2k2

cores/common/arduino/libraries/api/Serial/Serial.cpp

@@ -17,12 +17,95 @@ void SerialClass::adrParse(uint8_t c) {
 }
 #endif
 
-void SerialClass::begin(unsigned long baudrate, uint16_t config) {
+bool SerialClass::validatePins(pin_size_t rx, pin_size_t tx) {
+	// for each role (RX/TX) in each UART, fail validation if:
+	// - a pin is specified and no such role exists on the board, or
+	// - a pin is specified and is not among the supported pins for that role
+	switch (this->port) {
+#if LT_HW_UART0
+		case 0:
+			if (rx != PIN_INVALID
+#ifdef PINS_SERIAL0_RX
+				&& !ltArrayContains((pin_size_t[])PINS_SERIAL0_RX, rx)
+#endif
+			)
+				return false;
+			if (tx != PIN_INVALID
+#ifdef PINS_SERIAL0_TX
+				&& !ltArrayContains((pin_size_t[])PINS_SERIAL0_TX, tx)
+#endif
+			)
+				return false;
+			break;
+#endif
+
+#if LT_HW_UART1
+		case 1:
+			if (rx != PIN_INVALID
+#ifdef PINS_SERIAL1_RX
+				&& !ltArrayContains((pin_size_t[])PINS_SERIAL1_RX, rx)
+#endif
+			)
+				return false;
+			if (tx != PIN_INVALID
+#ifdef PINS_SERIAL1_TX
+				&& !ltArrayContains((pin_size_t[])PINS_SERIAL1_TX, tx)
+#endif
+			)
+				return false;
+			break;
+#endif
+
+#if LT_HW_UART2
+		case 2:
+			if (rx != PIN_INVALID
+#ifdef PINS_SERIAL2_RX
+				&& !ltArrayContains((pin_size_t[])PINS_SERIAL2_RX, rx)
+#endif
+			)
+				return false;
+			if (tx != PIN_INVALID
+#ifdef PINS_SERIAL2_TX
+				&& !ltArrayContains((pin_size_t[])PINS_SERIAL2_TX, tx)
+#endif
+			)
+				return false;
+			break;
+#endif
+
+		default:
+			return false;
+	}
+	return true;
+}
+
+void SerialClass::begin(unsigned long baudrate, uint16_t config, pin_size_t rx, pin_size_t tx) {
+	// let family code cleanup any resources
+	this->end();
+
+	// allocate data structure and ring buffer
 	if (!this->data) {
 		this->data	= new SerialData();
 		this->rxBuf = new SerialRingBuffer();
 	}
 
+	// use provided pins or those used previously
+	if (rx == PIN_INVALID)
+		rx = this->rx;
+	if (tx == PIN_INVALID)
+		tx = this->tx;
+	// nothing to configure if RX and TX are invalid
+	if (rx == PIN_INVALID && tx == PIN_INVALID)
+		return;
+	// validate if provided pins are valid for this UART port
+	if (!this->validatePins(rx, tx)) {
+		LT_E("Serial pin numbers RX=%d,TX=%d invalid for port %u", rx, tx, this->port);
+		return;
+	}
+	// store in SerialClass for family code to use
+	this->rx = rx;
+	this->tx = tx;
+
 	this->beginPrivate(baudrate, config);
 	// if (this->baudrate != baudrate || this->config != config)
 	this->configure(baudrate, config);

cores/common/arduino/libraries/api/Serial/Serial.h

@@ -23,6 +23,8 @@ class SerialClass : public HardwareSerial {
 	uint32_t baudrate{0};			  //!< currently set baudrate
 	uint16_t config{0};				  //!< currently set configuration
 
+	bool validatePins(pin_size_t rx, pin_size_t tx);
+
   private: /* family core */
 	void beginPrivate(unsigned long baudrate, uint16_t config);
 	void endPrivate();
@@ -35,12 +37,16 @@ class SerialClass : public HardwareSerial {
   public: /* common core */
 	SerialClass(uint32_t port, pin_size_t rx = PIN_INVALID, pin_size_t tx = PIN_INVALID) : port(port), rx(rx), tx(tx) {}
 
-	void begin(unsigned long baudrate, uint16_t config);
+	void begin(unsigned long baudrate, uint16_t config, pin_size_t rx, pin_size_t tx);
 	void end();
 	int available();
 	int peek();
 	int read();
 
+	inline void begin(unsigned long baudrate, uint16_t config) {
+		begin(baudrate, config, PIN_INVALID, PIN_INVALID);
+	}
+
 	inline void begin(unsigned long baudrate) {
 		begin(baudrate, SERIAL_8N1);
 	}