FPS_G511C3 fingerprint sensor fails to run sketches properly

Other Hardware Sensors
1

Hi guys,

Im using this sensor (GT-511C3) here

Along with this library

If I add the debug = true line to the sketches I get this:

FPS - Open
FPS - SEND: "55 AA 01 00 00 00 00 00 01 00 01 01"

but nothing else happens. Im using the code examples from the library itself. Im using a 985Ω resistor and a 1.46kΩ as a divider.

Connections are
Arduino---------FPS
5V -------------Vcc
GND -----------GND
4 ---------------Tx
5 ---0.985------Rx
|
------1.46kΩ-----GND

I have to open the serial monitor a few times after upload in order for any sketch to work. Below are the Blink and Enroll sketches and what they give once I get them to work after opening the SM about 3 or 5 times after upload.

Here is FPS_Blink.ino:

/* FPS_Enroll.ino - Library example for controlling the GT-511C3 Finger Print Scanner (FPS) Created by Josh Hawley, July 23rd 2013 Licensed for non-commercial use, must include this license message basically, Feel free to hack away at it, but just give me credit for my work =) TLDR; Wil Wheaton's Law This simple sketch turns the LED on and off similar to the Arduino blink sketch. It is used to show that communications are working. */ #include "FPS_GT511C3.h" #include "SoftwareSerial.h" // Hardware setup - FPS connected to: //  digital pin 4(arduino rx, fps tx) //  digital pin 5(arduino tx - 560ohm resistor fps tx - 1000ohm resistor - ground) // this brings the 5v tx line down to about 3.2v so we dont fry our fps FPS_GT511C3 fps(4, 5); void setup() { Serial.begin(9600);  //Serial.println("hi");  delay(100); fps.UseSerialDebug = true; // so you can see the messages in the serial debug screen fps.Open(); } void loop() { // FPS Blink LED Test fps.SetLED(true); // turn on the LED inside the fps delay(1000); fps.SetLED(false);// turn off the LED inside the fps delay(1000); }

When it works I get:

FPS - Open
FPS - SEND: "55 AA 01 00 00 00 00 00 01 00 01 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - LED on
FPS - SEND: "55 AA 01 00 01 00 00 00 12 00 13 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - LED off
FPS - SEND: "55 AA 01 00 00 00 00 00 12 00 12 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - LED on
FPS - SEND: "55 AA 01 00 01 00 00 00 12 00 13 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - LED off
FPS - SEND: "55 AA 01 00 00 00 00 00 12 00 12 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - LED on
FPS - SEND: "55 AA 01 00 01 00 00 00 12 00 13 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

Here is the FPS_Enroll.ino:

/***************************************************************** FPS_Enroll.ino - Library example for controlling the GT-511C3 Finger Print Scanner (FPS) Created by Josh Hawley, July 23rd 2013 Licensed for non-commercial use, must include this license message basically, Feel free to hack away at it, but just give me credit for my work =) TLDR; Wil Wheaton's Law #include "FPS_GT511C3.h" #include "SoftwareSerial.h" void setup() { Serial.begin(9600); //set up Arduino's hardware serial UART delay(100); fps.Open();         //send serial command to initialize fps fps.SetLED(true);   //turn on LED so fps can see fingerprint Enroll();          //begin enrolling fingerprint } void Enroll() { // Enroll test // find open enroll id int enrollid = 0; bool usedid = true; while (usedid == true) { usedid = fps.CheckEnrolled(enrollid); if (usedid==true) enrollid++; } fps.EnrollStart(enrollid); // enroll Serial.print("Press finger to Enroll #"); Serial.println(enrollid); while(fps.IsPressFinger() == false) delay(100); bool bret = fps.CaptureFinger(true); int iret = 0; if (bret != false) { Serial.println("Remove finger"); fps.Enroll1(); while(fps.IsPressFinger() == true) delay(100); Serial.println("Press same finger again"); while(fps.IsPressFinger() == false) delay(100); bret = fps.CaptureFinger(true); if (bret != false) { Serial.println("Remove finger"); fps.Enroll2(); while(fps.IsPressFinger() == true) delay(100); Serial.println("Press same finger yet again"); while(fps.IsPressFinger() == false) delay(100); bret = fps.CaptureFinger(true); if (bret != false) { Serial.println("Remove finger"); iret = fps.Enroll3(); if (iret == 0) { Serial.println("Enrolling Successful"); } else { Serial.print("Enrolling Failed with error code:"); Serial.println(iret); } } else Serial.println("Failed to capture third finger"); } else Serial.println("Failed to capture second finger"); } else Serial.println("Failed to capture first finger"); } void loop() { delay(100000); }

When it works I get this:

FPS - Open
FPS - SEND: "55 AA 01 00 00 00 00 00 01 00 01 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - LED on
FPS - SEND: "55 AA 01 00 01 00 00 00 12 00 13 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - CheckEnrolled
FPS - SEND: "55 AA 01 00 00 00 00 00 21 00 21 01"
FPS - RECV: "55 AA 01 00 04 10 00 00 31 00 45 01"

FPS - EnrollStart
FPS - SEND: "55 AA 01 00 00 00 00 00 22 00 22 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

Press finger to Enroll #0
FPS - IsPressFinger
FPS - SEND: "55 AA 01 00 01 00 00 00 26 00 27 01"
FPS - RECV: "55 AA 01 00 12 10 00 00 30 00 52 01"

FPS - IsPressFinger
FPS - SEND: "55 AA 01 00 01 00 00 00 26 00 27 01"
FPS - RECV: "55 AA 01 00 12 10 00 00 30 00 52 01"

...

FPS - IsPressFinger
FPS - SEND: "55 AA 01 00 01 00 00 00 26 00 27 01"
FPS - RECV: "55 AA 01 00 00 00 00 00 30 00 30 01"

FPS - CaptureFinger
FPS - SEND: "55 AA 01 00 01 00 00 00 60 00 61 01"
FPS - RECV: "55 AA 01 00 12 10 00 00 31 00 53 01"

Failed to capture first finger

And at this last CaptureFinger is when I pressed my finger to the reader.

2

I just replaced my 1/2k resistors for 10/20k resistors and it seems to work "better". With enroll I'm able to get to the enroll prompt in the serial monitor and I even got 2 finger reads and the 3rd one failed. Unfortunately it seems that once something fails, the code isn't really designed to handle that and restart, it just hangs. I'll keep trying but it seems to be a voltage issue. I'm guessing it's very sensitive and tiny variances in resistors and perhaps now power source (I'm using the 5v from the USB-pc powered Arduino) and perhaps even the movement of the sensor when pressed may be causing the voltage issue which causes the comm issue which hangs the code.