I have a setup where I’m trying to hook a Grove NFC (or any PN532 chip) in I2C mode. It works great for sending raw NFC messages but when I try to do NDEF (peer-to-peer) it doesn’t work because the NDEF packets are bigger than the I2C buffer size. I think it needs to be 44 bytes in order to work…

I was wondering if it was possible to change this value and if so, do it without downloading the whole firmware source to change the value.

If this isn’t possible, does anyone know of a cheap ~$20 PN532 that supports SPI? I have the code working with the Adafruit PN532 and Seeed PN532 shield over SPI but I would like something smaller/cheaper like the Grove.


@jlkalberer Have you looked into MFRC522? It supports SPI but it does not include an integrated uController like the PN532. You can get a cheap test board with the chip integrated for under $5 on ebay. I’ve used it using SPI with the Sparkcore with good results.

Thanks. I’ll definitely look into this. Is it RFID though? I did a quick google search and that is what it looks like…

Anyway, I currently have a freelancer building a NFC/Photon PCB for me. I think it’s $8-10 per PN532 so it should be fine… I just wanted a cheaper shield or board I could buy online. Most of them were $30+

Hi, did you ever get anywhere with this?

I didn’t find anything cheaper but I am getting the PCB built which is specific to my app.