1

Here's the whole error:

 Arduino: 1.6.7 (Windows 7), Board: "Arduino/Genuino Uno"

 *\readMifare\readMifare.ino: In function 'void loop()':

 readMifare:113: error: expected primary-expression before ']' token

    if (uid[] == { 0x04, 0xEC, 0x89, 0x32, 0x55, 0x42, 0x80 }) {

            ^

 readMifare:113: error: expected primary-expression before '{' token

    if (uid[] == { 0x04, 0xEC, 0x89, 0x32, 0x55, 0x42, 0x80 }) {

                 ^

 readMifare:113: error: expected ')' before '{' token

 readMifare:121: error: expected '}' at end of input

    }

    ^

 exit status 1
 expected primary-expression before ']' token

   This report would have more information with
   "Show verbose output during compilation"
   enabled in File > Preferences.

Here's the code

 #include <Wire.h>
 #include <SPI.h>
 #include <Adafruit_PN532.h>

 // If using the breakout with SPI, define the pins for SPI communication.
 #define PN532_SCK  (2)
 #define PN532_MOSI (3)
 #define PN532_SS   (4)
 #define PN532_MISO (5)
 // If using the breakout or shield with I2C, define just the pins connected
 // to the IRQ and reset lines.  Use the values below (2, 3) for the shield!
 #define PN532_IRQ   (2)
 #define PN532_RESET (3)  // Not connected by default on the NFC Shield

 // Uncomment just _one_ line below depending on how your breakout or shield
 // is connected to the Arduino:

 // Use this line for a breakout with a software SPI connection (recommended):
 Adafruit_PN532 nfc(PN532_SCK, PN532_MISO, PN532_MOSI, PN532_SS);

 // Use this line for a breakout with a hardware SPI connection.  Note that
 // the PN532 SCK, MOSI, and MISO pins need to be connected to the Arduino's
 // hardware SPI SCK, MOSI, and MISO pins.  On an Arduino Uno these are
 // SCK = 13, MOSI = 11, MISO = 12.  The SS line can be any digital IO pin.
 //Adafruit_PN532 nfc(PN532_SS);

 // Or use this line for a breakout or shield with an I2C connection:
 //Adafruit_PN532 nfc(PN532_IRQ, PN532_RESET);

 #if defined(ARDUINO_ARCH_SAMD)
 // for Zero, output on USB Serial console, remove line below if using      programming port to program the Zero!
 // also change #define in Adafruit_PN532.cpp library file
 #define Serial SerialUSB
 #endif
 #include <Servo.h>

 Servo servo1;

 void setup(void) {
   #ifndef ESP8266
   while (!Serial); // for Leonardo/Micro/Zero
   #endif
   Serial.begin(115200);
   Serial.println("Hello!");

   nfc.begin();

   uint32_t versiondata = nfc.getFirmwareVersion();
   if (! versiondata) {
     Serial.print("Didn't find PN53x board");
     while (1); // halt
   }
   // 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);

   // configure board to read RFID tags
   nfc.SAMConfig();

   Serial.println("Waiting for an ISO14443A Card ...");
   servo1.attach(9); 
 }


 void loop(void) {
   uint8_t success;
   uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };  // Buffer to store the returned UID
   uint8_t uidLength;                        // Length of the UID (4 or 7 bytes depending on ISO14443A card type)

   // Wait for an ISO14443A type cards (Mifare, etc.).  When one is found
   // 'uid' will be populated with the UID, and uidLength will indicate
   // if the uid is 4 bytes (Mifare Classic) or 7 bytes (Mifare Ultralight)
   success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength);

   if (uid[] = { 0x04, 0xEC, 0x89, 0x32, 0x55, 0x42, 0x80 }) {

      int position;
      for(position = 0; position < 180; position += 2){
       servo1.write(position);
       delay(20);
      }

   }

Please note that I'm using an example from the Adafruit official PN532 library examples and trying to edit it.

  • 1
    You probably do not want an '=' in the if statement. What example had this? – Dave X Feb 16 '16 at 19:01
  • This is what I added, still new though, so what should I input? – Dahacker305 Feb 16 '16 at 19:04
  • 1
    To compare you use ==. = is for assignment. Common mistake, even by the professionals. – Gerben Feb 16 '16 at 19:36
3

I wouldn't use strncmp because the UID might have zeroes in it. This looks safer:

   uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };  // Buffer to store the returned UID
   uint8_t uidLength;                        // Length of the UID (4 or 7 bytes depending on ISO14443A card type)

   const uint8_t wantedUid [] = { 0x04, 0xEC, 0x89, 0x32, 0x55, 0x42, 0x80 };

   // Wait for an ISO14443A type cards (Mifare, etc.).  When one is found
   // 'uid' will be populated with the UID, and uidLength will indicate
   // if the uid is 4 bytes (Mifare Classic) or 7 bytes (Mifare Ultralight)
   success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength);

   if (success && 
      uidLength == sizeof (wantedUid) &&
      memcmp (uid, wantedUid, sizeof wantedUid) == 0) {
      ...

I threw in a test for the uidLength being the expected size, otherwise you might find a 4-byte card happens to match the first four bytes of the wanted UID.

memcmp compares a block of memory for the number of bytes you specify. It returns zero on a match.

1

You probably need something like:

uint8_t uidTarget[] = { 0x04, 0xEC, 0x89, 0x32, 0x55, 0x42, 0x80 };

...
if (success && !strncmp((const char*) uidTarget,(const char*)uidSource,8)) {

Your '=' tries to do an assignment, and an '==' would check if the pointers to the arrays are identical, rather than the contents of the arrays. strncmp() tests equality of strings of characters, and the (const char*) casts the uint8_t values as characters.

Nick Gammon's answer is better.

  • added what you told me to add, error: readMifare:113: error: invalid conversion from 'uint8_t* {aka unsigned char*}' to 'const char*' [-fpermissive] if (success && !strncmp(uid,{ 0x04, 0xEC, 0x89, 0x32, 0x55, 0x42, 0x80 },8)) { readMifare:113: error: cannot convert '<brace-enclosed initializer list>' to 'const char*' for argument '2' to 'int strncmp(const char*, const char*, size_t)' readMifare:121: error: expected '}' at end of input } exit status 1 invalid conversion from 'uint8_t* {aka unsigned char*}' to 'const char*' [-fpermissive] – Dahacker305 Feb 16 '16 at 19:21
  • @Dahacker305: remove the const. – Edgar Bonet Feb 16 '16 at 20:23
  • "if (success && !strncmp(uid,{ 0x04, 0xEC, 0x89, 0x32, 0x55, 0x42, 0x80 },8))" - no you cannot do that. The ID must be an array variable. – Mikael Patel Feb 17 '16 at 10:24

Not the answer you're looking for? Browse other questions tagged or ask your own question.