Help with basic RFID reader code

Projects Programming
1

I have an 12LA reader hooked to my UNO. I am using code written by Barragan. The reader works great but now I need to compare the read to known tags. This is what the serial is giving me on a tag read.

6A 00 49 F6 B2 - five bytes of HEX

I want to compare this to known tag values so I can determine if it is a match.

RFID_Read.ino (2.6 KB)

2

I want to compare this to known tag values so I can determine if it is a match

You have permission.

3

You need to get those bytes into a single number.
Use a long long type of variable to hold both your required token and what is returned from the reader. Call it say readToken.

Put the reader's number in a byte at a time by logic ORing the number with the byte.
So shift the long long up 8 places, OR the last byte, and repeat untill all the bytes are in.
For your known token just declare the number like this

long long authorised = 0x6A0049F6B2;

then to test just use an if statement like :-

if ( authorised == readToken) { // do your thing
}
4

You've collected the data into an array that you print. It's trivial to use memcmp() or a for loop to compare that array to another array.

5

I am not sure how the string is received from serial even though the console shows HEX. I tried a memcmp() with my value, mytag,.
byte mytag[5] = {01101010, 0000, 01001001, 11110110, 10110010}; i
an array of bytes.
The console prints this array as
6A049F6B2
while the card read shows up on the console as
6A0049F6B2

if (memcmp(mybyte, mytag, 5) == 0){
Serial.print("yes");
}

No match yet

I built mybyte in the same for loop that prints each byte of the read card to the screen..
Not sure if I;m dealing with apples and oranges. The HEX number of the card would not fit into any number type. that I tries

6 
  byte mytag[5] = {01101010, 0000, 01001001, 11110110, 10110010}; i

Do those look like bytes to you?

byte goodTag[] = { 0x6A, 0x00, 0x49, 0xF6, 0xB2 };
7

It might be a seriese of zeros and ones to you but the compiler sees those as decimal numbers unless you tell it otherwise.

8

Grumpy_Mike:
It might be a seriese of zeros and ones to you but the compiler sees those as decimal numbers unless you tell it otherwise.

Well, he did for the first three - he told the compiler they were octal numbers.

9

Fixed. Thanks you for the help. I am a little new to serial like this but I have done work on displays, Never done learning. That;s why I'm here. I will clean the code up and leave it here later for another beginner. Thanks again.

R