PN532 vs KBR1: one is reading backwards

So, i have a simple issue with no explanation that i can think of…
I recently got some pn532s for my car project and i have a kbr1 that came with my NExT.
the 7 byte uid of the next seems to read the same on both of them but the card and keychain fob that came with the pn532 have 4 byte UIDs and they read in reverse order from the pn to the kbr1…

also to clarify, the bytes read in reverse order, not the whole thing
KBR1: b7967729
pn532: 0x29 0x77 0x96 0xb7 0x0 0x0 0x0

whats causing this?

I believe the PN532 is MSB. Mifare chips are LSB. So MSB reads it backwards.

Would you mind elaborating on what these acronyms mean?

Least Significant Byte and Most Significant Byte. Basically they read in opposite directions.

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Check whichever PN532 library you are using to either change modes or convert the data. It looks like the Adafruit library has a function to convert from one to the other.

thank you very much!
im using elechouse’s library which is a modified adafruit one but its not really a problem i need to fix, its just something i was curious about

Have you tried scanning the other side of the fob to make it read forwards… looks like you were scanning the wrong side of the card… sorry, couldn’t resist :slight_smile: