**1)**I want to ask that why the "uint8_t getFingerprintID()" function is declared whereas there is no calling of this function in the void loop(). The only function used is "int getFingerprintIDez()". Why did they give "uint8_t getFingerprintID()" function for no use?
**2)**Why did the initialize "int getFingerprintIDez();" at first without any code and writing the code later on at the last? It should not compile?
**3)**Why did they give "while (1)" in the void setup, further, with a space in between them?
/***************************************************
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 <SoftwareSerial.h>
int getFingerprintIDez();
// pin #2 is IN from sensor (GREEN wire)
// pin #3 is OUT from arduino (WHITE wire)
SoftwareSerial mySerial(2, 3);
Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial);
// On Leonardo/Micro or others with hardware serial, use those! #0 is green wire, #1 is white
//Adafruit_Fingerprint finger = Adafruit_Fingerprint(&Serial1);
void setup()
{
while (!Serial); // For Yun/Leo/Micro/Zero/...
Serial.begin(9600);
Serial.println("Adafruit finger detect test");
// 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);
}
Serial.println("Waiting for valid finger...");
}
void loop() // run over and over again
{
getFingerprintIDez();
delay(50); //don't ned to run this at full speed.
}
uint8_t getFingerprintID() {
uint8_t p = finger.getImage();
switch (p) {
case FINGERPRINT_OK:
Serial.println("Image taken");
break;
case FINGERPRINT_NOFINGER:
Serial.println("No finger detected");
return p;
case FINGERPRINT_PACKETRECIEVEERR:
Serial.println("Communication error");
return p;
case FINGERPRINT_IMAGEFAIL:
Serial.println("Imaging error");
return p;
default:
Serial.println("Unknown error");
return p;
}
// OK success!
p = finger.image2Tz();
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!
p = finger.fingerFastSearch();
if (p == FINGERPRINT_OK) {
Serial.println("Found a print match!");
} else if (p == FINGERPRINT_PACKETRECIEVEERR) {
Serial.println("Communication error");
return p;
} else if (p == FINGERPRINT_NOTFOUND) {
Serial.println("Did not find a match");
return p;
} else {
Serial.println("Unknown error");
return p;
}
// found a match!
Serial.print("Found ID #"); Serial.print(finger.fingerID);
Serial.print(" with confidence of "); Serial.println(finger.confidence);
}
// 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;
// found a match!
Serial.print("Found ID #"); Serial.print(finger.fingerID);
Serial.print(" with confidence of "); Serial.println(finger.confidence);
return finger.fingerID;
}
1/ this is probably a small remaining part of writing their demo code. indeed useless and not even included by the compiler as not called. but good for you to study
2/ the first declaration is to let the pre-processor know that this function will be declared later. sometimes it matters to help compiling.
3/ the while(1) happens when the fingerprint reader is not found, then there is no point going into the loop because the hardware is not there. so this just puts your Arduino in an infinite cycle after displaying an error message
and 2) int getFingerprintIDez(); is a function prototype (Google will explain) not usually needed in Arduino programs because they are built and added to the code for you during compilation so you don't see them.
In the Arduino environment int and uint8_t are the same data type.
In order to halt the program if the fingerprint reader is not detected. In C spaces are ignored unless in strings.