API extended with a new function: You can now call the FPS constructor with the desired baud rate you want to establish communications, as additional parameter. Furthermore, comms won't fail while initializing if the FPS baud rate was established to something else than 9600.

Author: Fasgort

src/FPS_GT511C3.cpp

@@ -316,13 +316,15 @@ void Data_Packet::SendToSerial(uint8_t data[], uint16_t length)
 #pragma region -= Constructor/Destructor =-
 #endif  //__GNUC__
 // Creates a new object to interface with the fingerprint scanner
+// It will establish the communication to the desired baud rate if defined
 FPS_GT511C3::FPS_GT511C3(uint8_t rx, uint8_t tx, uint32_t baud)
 	: _serial(rx,tx)
 {
 	pin_RX = rx;
 	pin_TX = tx;
-	_serial.begin(baud);
 	this->UseSerialDebug = false;
+    this->Started = false;
+    desiredBaud = baud;
 };
 
 // destructor
@@ -338,8 +340,10 @@ FPS_GT511C3::~FPS_GT511C3()
 #pragma region -= Device Commands =-
 #endif  //__GNUC__
 //Initialises the device and gets ready for commands
-void FPS_GT511C3::Open()
+//Returns true if the communication established
+bool FPS_GT511C3::Open()
 {
+    if (!Started) Start();
 	if (UseSerialDebug) Serial.println("FPS - Open");
 	Command_Packet* cp = new Command_Packet();
 	cp->Command = Command_Packet::Commands::Open;
@@ -351,8 +355,11 @@ void FPS_GT511C3::Open()
 	delete cp;
 	SendCommand(packetbytes, 12);
 	Response_Packet* rp = GetResponse();
+	bool retval = true;
+	if (rp->ACK == false) retval = false;
 	delete rp;
 	delete packetbytes;
+	return retval;
 }
 
 // According to the DataSheet, this does nothing...
@@ -413,8 +420,7 @@ bool FPS_GT511C3::ChangeBaudRate(uint32_t baud)
 {
     if ((baud == 9600) || (baud == 19200) || (baud == 38400) || (baud == 57600) || (baud == 115200))
 	{
-
-		if (UseSerialDebug) Serial.println("FPS - ChangeBaudRate");
+        if (UseSerialDebug) Serial.println("FPS - ChangeBaudRate");
 		Command_Packet* cp = new Command_Packet();
 		cp->Command = Command_Packet::Commands::ChangeBaudRate;
 		cp->ParameterFrom(baud);
@@ -847,6 +853,114 @@ bool FPS_GT511C3::GetRawImage()
 #ifndef __GNUC__
 #pragma region -= Private Methods =-
 #endif  //__GNUC__
+// Configures the device correctly for communications at the desired baud rate
+void FPS_GT511C3::Start()
+{
+	Command_Packet* cp = new Command_Packet();
+	cp->Command = Command_Packet::Commands::Open;
+	cp->Parameter[0] = 0x00;
+	cp->Parameter[1] = 0x00;
+	cp->Parameter[2] = 0x00;
+	cp->Parameter[3] = 0x00;
+	uint8_t* packetbytes = cp->GetPacketBytes();
+	delete cp;
+
+	uint32_t baud = desiredBaud;
+    if (!(baud == 9600) && !(baud == 19200) && !(baud == 38400) && !(baud == 57600) && !(baud == 115200)) baud=9600;
+	uint32_t actualBaud = 0;
+	uint32_t BaudRates[5] = {9600, 19200, 38400, 57600, 115200};
+	for(uint8_t i = 0; i<5; i++) // Trying to find FPS baud rate
+    {
+        if(UseSerialDebug)
+        {
+            Serial.print("Establishing connection with FPS at baud rate: ");
+            Serial.print(BaudRates[i]);
+            Serial.println();
+        }
+        _serial.begin(BaudRates[i]);
+        _serial.listen();
+        SendCommand(packetbytes, 12);
+        delay(100);
+
+        uint8_t firstbyte = 0;
+        uint8_t secondbyte = 0;
+        bool done = false;
+        uint8_t byteCount = 0;
+        while (done == false && byteCount<100)
+        {
+            byteCount++;
+            if(_serial.peek() == -1) break;
+            firstbyte = (uint8_t)_serial.read();
+            if (firstbyte == Response_Packet::COMMAND_START_CODE_1)
+            {
+                if(_serial.peek() == -1) break;
+                secondbyte = (uint8_t)_serial.read();
+                if (secondbyte == Response_Packet::COMMAND_START_CODE_2)
+                {
+                    done = true;
+                }
+            }
+        }
+        if (!done)
+        {
+            while (_serial.available()) _serial.read(); // Clear Serial buffer
+        } else
+        {
+            uint8_t* resp = new uint8_t[12];
+            resp[0] = firstbyte;
+            resp[1] = secondbyte;
+            for (uint8_t i=2; i < 12; i++)
+            {
+                while (_serial.available() == false) delay(10);
+                resp[i]= (uint8_t) _serial.read();
+            }
+            if (UseSerialDebug)
+            {
+                Response_Packet* rp = new Response_Packet(resp, UseSerialDebug);
+                Serial.print("FPS - RECV: ");
+                SendToSerial(rp->RawBytes, 12);
+                Serial.println();
+                Serial.println();
+                delete rp;
+            }
+            delete resp;
+            actualBaud = BaudRates[i];
+            break;
+        }
+    }
+
+    if(UseSerialDebug)
+    {
+        Serial.print("Connection established succesfully. FPS baud rate was: ");
+        Serial.print(actualBaud);
+        Serial.println();
+        Serial.println();
+    }
+
+    if (actualBaud == 0) while(true)
+    {
+        if(UseSerialDebug)
+        {
+            Serial.print("EXCEPTION: FPS didn't answer to communications. Code execution stopped.");
+            Serial.println();
+        }
+        delay(1000); // Something went terribly wrong with the FPS, and you aren't allowed to leave
+    }
+
+    if (actualBaud != baud)
+    {
+        if(UseSerialDebug)
+        {
+            Serial.print("Undesired baud rate. Changing baud rate to: ");
+            Serial.print(baud);
+            Serial.println();
+            Serial.println();
+        }
+        ChangeBaudRate(baud);
+    }
+    Started = true;
+}
+
 // Sends the command to the software serial channel
 void FPS_GT511C3::SendCommand(uint8_t cmd[], uint16_t length)
 {

src/FPS_GT511C3.h

@@ -181,11 +181,13 @@ class FPS_GT511C3
  public:
 	// Enables verbose debug output using hardware Serial
 	bool UseSerialDebug;
+	uint32_t desiredBaud;
 
 #ifndef __GNUC__
 	#pragma region -= Constructor/Destructor =-
 #endif  //__GNUC__
 	// Creates a new object to interface with the fingerprint scanner
+	// It will establish the communication to the desired baud rate if defined
 	FPS_GT511C3(uint8_t rx, uint8_t tx, uint32_t baud = 9600);
 
 	// destructor
@@ -199,7 +201,8 @@ class FPS_GT511C3
 	#pragma region -= Device Commands =-
 #endif  //__GNUC__
 	//Initialises the device and gets ready for commands
-	void Open();
+	//Returns true if the communication established
+	bool Open();
 
 	// Does not actually do anything (according to the datasheet)
 	// I implemented open, so had to do closed too... lol
@@ -361,11 +364,18 @@ class FPS_GT511C3
 	void SendToSerial(uint8_t data[], uint16_t length);
 
 private:
-	 void SendCommand(uint8_t cmd[], uint16_t length);
-	 Response_Packet* GetResponse();
-	 void GetData(uint16_t length);
-	 uint8_t pin_RX,pin_TX;
-	 SoftwareSerial _serial;
+
+    // Indicates if the communication was configured for the first time
+	bool Started;
+
+    //Configures the device correctly for communications at the desired baud rate
+    void Start();
+
+    void SendCommand(uint8_t cmd[], uint16_t length);
+    Response_Packet* GetResponse();
+    void GetData(uint16_t length);
+    uint8_t pin_RX,pin_TX;
+    SoftwareSerial _serial;
 };