PN532 vs KBR1: one is reading backwards

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1

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?

2

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

3

Would you mind elaborating on what these acronyms mean?

4

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

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5

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.

6

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

7

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:

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