Arduino NFC PN532

Question

Hello im trying to make a program to compare the NFC tag #ID, im very used to Arduino, but im not used to SPI Programming.

i searched a lot, but i dont really know what i need exactly.

im trying match the NFC tag #ID and the variable NFC1.

Can anyone help me? please?

i just need some info/help to make the if statement work.

#include <PN532.h>
#include <SPI.h>

//SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK)

/*Chip select pin can be connected to D10 or D9 which is hareware optional*/
/*if you the version of NFC Shield from SeeedStudio is v2.0.*/
#define PN532_CS 10
PN532 nfc(PN532_CS);
#define  NFC_DEMO_DEBUG 1

int BUZZER = 6;
uint32_t NFC1 = 3795120787;
int NFC2 = 3262404755;
int NFC3 = 46356883;
int NFC4 = 35320979;
int NFC5 = 3257334163;

void setup(void) {

pinMode(BUZZER, OUTPUT);
#ifdef NFC_DEMO_DEBUG
Serial.begin(9600);
Serial.println("Hello!");
#endif
nfc.begin();

uint32_t versiondata = nfc.getFirmwareVersion();
if (! versiondata) {
#ifdef NFC_DEMO_DEBUG
Serial.print("Didn't find PN53x board");
Serial.print("");
#endif
while (1); // halt
}
#ifdef NFC_DEMO_DEBUG
// Got ok data, print it out!
Serial.print("Found chip PN5"); 
Serial.println((versiondata>>24) & 0xFF, HEX);
/*Serial.print("Firmware ver. "); 
Serial.print((versiondata>>16) & 0xFF, DEC);
Serial.print('.'); 
Serial.println((versiondata>>8) & 0xFF, DEC);
Serial.print("Supports "); 
Serial.println(versiondata & 0xFF, HEX);*/
#endif
// configure board to read RFID tags and cards
nfc.SAMConfig();
}


void loop(void) {
uint32_t id;
// look for MiFare type cards
id = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A);

if (id != 0) {
#ifdef NFC_DEMO_DEBUG
Serial.println("");
Serial.print("Card #"); 
Serial.println(id);
analogWrite(BUZZER, 50);
delay(100);
analogWrite(BUZZER, 0);
delay(1000);
#endif
//char ch = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A);

if(NFC1 = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A)){

    analogWrite(6, 255);
    delay(250);
    analogWrite(6, 0);
  /*analogWrite(BUZZER, 50);
  delay(50);
  analogWrite(BUZZER, 0);
  delay(50);
  analogWrite(BUZZER, 50);
  delay(50);
  analogWrite(BUZZER, 0);*/}

  else {
    analogWrite(5, 255);
    delay(250);
    analogWrite(5, 0);
  /*analogWrite(BUZZER, 50);
  delay(100);
  analogWrite(BUZZER, 0);
  delay(100);
  analogWrite(BUZZER, 50);
  delay(100);
  analogWrite(BUZZER, 0);
  delay(100);
  analogWrite(BUZZER, 50);
  delay(100);
  analogWrite(BUZZER, 0);*/}
  }
   }

Answer 1

Common mistake and the compiler could have helped you

Change this line:

uint32_t NFC1 = 3795120787;

To this line:

const uint32_t NFC1 = 3795120787;

You will now get a compiler error, which would have resulted in you going :o.

This line needs a ==, not a =. Not this:

if(NFC1 = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A)){   / doh!

This:

if(NFC1 == nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A)){   / ahh

---

Side note, this is a common typing error and reason why

if(1 == somevar)  // is superior to

if(somevar == 1)  // something that seems exactly the same

Because the compiler will tell you

if(1 = somevar)  // no, you can't assign to a constant

if(somevar = 1)  // okay, whatever you want boss

This advice is from "Writing Solid Code", Maguire and Moore, and has served me well.