PN532 NFC Reader¶

The PN532 is an NFC/RFID reader/writer module connected to the WT32-SC01 Plus via I²C.

Role in SpoolmanScale¶

The PN532 detects NFC tags placed on the reader surface and reads their UID. SpoolmanScale uses this UID to identify spools in Spoolman — no data is written to the tag.

Two tag flows are supported:

Bambu Lab spools — MIFARE Classic tags with encrypted data (4-byte UID)
Third-party spools — NTAG / MIFARE Ultralight sticker tags (7-byte UID)

Specifications¶

Property	Value
Module	PN532 breakout board
Interface	I²C
I²C Address	0x24
Frequency	13.56 MHz
Protocol	ISO 14443A
WT32 Pins	SDA → GPIO10, SCL → GPIO11, RST → GPIO12

I²C Mode Setup¶

The PN532 must be set to I²C mode before wiring. Two jumpers on the back of the module select the interface.

Jumper 1: CLOSED
Jumper 2: OPEN

→ I²C mode active

Set jumpers BEFORE soldering

Changing the mode jumpers after soldering is difficult. Set I²C mode first.

Compatible Tags¶

Not all NFC tags work with SpoolmanScale. See the full NFC Tag Compatibility Guide for:

Which tags to buy
Which tags will NOT work and why
How to identify tags you already have

Short answer: Any NTAG213, NTAG215, NTAG216 or MIFARE Ultralight sticker tag works. MIFARE Classic does not.

Wiring¶

See the Wiring Guide for the full pinout and assembly instructions.