Problems with fingerprint sensor

Hi,

I have some troubles to get running my sketch. There should be two modes for the fingerprint scanner, one is called “SCAN_ACTIVE”, the other mode is called “ENROLL”.
Simply I switch the mode over Serial (actually over IDE console), but If I use finger.getImage(); in the other function, it crashes/reboots my Arduino Nano v3.0 (ATmega238) instantly.

If I only have getFingerprintEnroll(id) have enabled, it crashes (i don’t need to switch the mode from SCAN_ACTIVE to ENROLL), I absolutely have no idea why…

My code:

/*************************************************** 
  This is an example sketch for our optical Fingerprint sensor

  Designed specifically to work with the Adafruit BMP085 Breakout 
  ----> http://www.adafruit.com/products/751

  These displays use TTL Serial to communicate, 2 pins are required to 
  interface
  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/


#include <Adafruit_Fingerprint.h>
#include <Timer.h>


int getFingerprintIDez();

String mode;
String content = "";
int id = 0;
int val;
// pin #2 is IN from sensor (GREEN wire)
// pin #3 is OUT from arduino  (WHITE wire)
SoftwareSerial fingerprint(2, 3);

Adafruit_Fingerprint finger = Adafruit_Fingerprint(&fingerprint);
Timer t;

void setup()  
{
  while (!Serial);  // For Yun/Leo/Micro/Zero/...
  
  Serial.begin(9600);
  finger.begin(9600);
  Serial.println("Adafruit finger detect test\n");

  // set the data rate for the sensor serial port
  finger.begin(57600);
  
  if (finger.verifyPassword()) {
    Serial.println("Found fingerprint sensor!!");
  } else {
    Serial.println("Did not find fingerprint sensor :(");
    while (1);
  }
  mode = "SCAN_ACTIVE";
  Serial.print(mode+"\n");
  int tickEvent1 = t.every(0, listenWemos);
  int tickEvent2 = t.every(0, listenFP);
}

void listenWemos() {
  while (Serial.available() > 0) {
    mode = Serial.readStringUntil('\n');
    val = Serial.parseInt();
    Serial.print("Received:" + mode+ ":"+val+"\n");
  }
}

void listenFP() {
  if(mode == "SCAN_ACTIVE") {
    id = getFingerprintIDez();
    if(id > 0) {
      Serial.print(mode + "\n");
      Serial.print(id);
      id = 0;
    }
  } else if(mode == "ENROLL") {
    Serial.println("Ready to enroll a fingerprint! Please Type in the ID # you want to save this finger as...");
    id = readnumber();
    Serial.print("Enrolling ID #");
    Serial.println(id);
    
    while (!  getFingerprintEnroll(id) );
  }
}

void loop()
{
  t.update();

}

// returns -1 if failed, otherwise returns ID #
int getFingerprintIDez() {
  uint8_t p = finger.getImage();
  if (p != FINGERPRINT_OK)  return -1;

  p = finger.image2Tz();
  if (p != FINGERPRINT_OK)  return -1;

  p = finger.fingerFastSearch();
  if (p != FINGERPRINT_OK)  return -1;
  return finger.fingerID; 
}



// ENROLL

uint8_t readnumber(void) {
  uint8_t num = 0;
  boolean validnum = false; 
  while (1) {
    while (! Serial.available());
    char c = Serial.read();
    if (isdigit(c)) {
       num *= 10;
       num += c - '0';
       validnum = true;
    } else if (validnum) {
      return num;
    }
  }
}

uint8_t getFingerprintEnroll(int id) {

  int p = -1;
  Serial.print("Waiting for valid finger to enroll as #"); Serial.println(id);
  while (p != FINGERPRINT_OK) {
    p = finger.getImage();
    switch (p) {
    case FINGERPRINT_OK:
      Serial.println("Image taken");
      break;
    case FINGERPRINT_NOFINGER:
      Serial.println(".");
      break;
    case FINGERPRINT_PACKETRECIEVEERR:
      Serial.println("Communication error");
      break;
    case FINGERPRINT_IMAGEFAIL:
      Serial.println("Imaging error");
      break;
    default:
      Serial.println("Unknown error");
      break;
    }
  }

  // OK success!

  p = finger.image2Tz(1);
  switch (p) {
    case FINGERPRINT_OK:
      Serial.println("Image converted");
      break;
    case FINGERPRINT_IMAGEMESS:
      Serial.println("Image too messy");
      return p;
    case FINGERPRINT_PACKETRECIEVEERR:
      Serial.println("Communication error");
      return p;
    case FINGERPRINT_FEATUREFAIL:
      Serial.println("Could not find fingerprint features");
      return p;
    case FINGERPRINT_INVALIDIMAGE:
      Serial.println("Could not find fingerprint features");
      return p;
    default:
      Serial.println("Unknown error");
      return p;
  }
  
  Serial.println("Remove finger");
  delay(2000);
  p = 0;
  while (p != FINGERPRINT_NOFINGER) {
    p = finger.getImage();
  }
  Serial.print("ID "); Serial.println(id);
  p = -1;
  Serial.println("Place same finger again");
  while (p != FINGERPRINT_OK) {
    p = finger.getImage();
    switch (p) {
    case FINGERPRINT_OK:
      Serial.println("Image taken");
      break;
    case FINGERPRINT_NOFINGER:
      Serial.print(".");
      break;
    case FINGERPRINT_PACKETRECIEVEERR:
      Serial.println("Communication error");
      break;
    case FINGERPRINT_IMAGEFAIL:
      Serial.println("Imaging error");
      break;
    default:
      Serial.println("Unknown error");
      break;
    }
  }

  // OK success!

  p = finger.image2Tz(2);
  switch (p) {
    case FINGERPRINT_OK:
      Serial.println("Image converted");
      break;
    case FINGERPRINT_IMAGEMESS:
      Serial.println("Image too messy");
      return p;
    case FINGERPRINT_PACKETRECIEVEERR:
      Serial.println("Communication error");
      return p;
    case FINGERPRINT_FEATUREFAIL:
      Serial.println("Could not find fingerprint features");
      return p;
    case FINGERPRINT_INVALIDIMAGE:
      Serial.println("Could not find fingerprint features");
      return p;
    default:
      Serial.println("Unknown error");
      return p;
  }
  
  // OK converted!
  Serial.print("Creating model for #");  Serial.println(id);
  
  p = finger.createModel();
  if (p == FINGERPRINT_OK) {
    Serial.println("Prints matched!");
  } else if (p == FINGERPRINT_PACKETRECIEVEERR) {
    Serial.println("Communication error");
    return p;
  } else if (p == FINGERPRINT_ENROLLMISMATCH) {
    Serial.println("Fingerprints did not match");
    return p;
  } else {
    Serial.println("Unknown error");
    return p;
  }   
  
  Serial.print("ID "); Serial.println(id);
  p = finger.storeModel(id);
  if (p == FINGERPRINT_OK) {
    Serial.println("Stored!");
  } else if (p == FINGERPRINT_PACKETRECIEVEERR) {
    Serial.println("Communication error");
    return p;
  } else if (p == FINGERPRINT_BADLOCATION) {
    Serial.println("Could not store in that location");
    return p;
  } else if (p == FINGERPRINT_FLASHERR) {
    Serial.println("Error writing to flash");
    return p;
  } else {
    Serial.println("Unknown error");
    return p;
  }   
}

The whole is a combination of

and

I hope someone can help me!