Connecting PN532 to M5StickC plus2 via user i2c pins

[MurzikYEET]

Hello, how do I connect the NFC module PN532 via i2c using pins SDA>G26 and SCL>G25/G36??
Is there, for example, something in brucePins.conf on device to set your pins for PN532? (NOT "rfidmodule" : int_value, PINS ONLY)

[bad-antics]

Yes, you can configure custom I2C pins for the PN532 on the M5StickC Plus 2 via the brucePins.conf file. Here's how:

Configure I2C Pins in brucePins.conf

On your SD card (or SPIFFS), create/edit brucePins.conf and add:

{
  "i2cSDA": 26,
  "i2cSCL": 0
}

Important for M5StickC Plus 2: G25 is input-only on ESP32 (GPIO25 is actually the DAC output on original ESP32, but on PICO variants it may behave differently). G36 is input-only on the ESP32 and cannot drive the I2C SCL line (which requires bidirectional communication).

Recommended pin combinations for M5StickC Plus 2:

• SDA: G26, SCL: G0 (both support bidirectional I/O)
• SDA: G26, SCL: G32 (if available on your header)

PN532 I2C Wiring

Make sure your PN532 is set to I2C mode (check the DIP switches on the module):

PN532 Pin	M5StickC Plus 2
SDA	G26
SCL	G0 (or G32)
VCC	3.3V
GND	GND

Verify Detection

After connecting and configuring:

1. Power on the M5StickC Plus 2
2. Navigate to Others > I2C Scanner (if available in your Bruce version)
3. The PN532 should show up at address 0x24 (default I2C address)
4. Then go to RFID menu and it should detect the PN532 module

Troubleshooting

• If the PN532 isn't detected, double-check the DIP switches are set to I2C mode (typically: SW1=ON, SW2=OFF or similar depending on your board variant)
• Make sure you're using 3.3V, not 5V (ESP32 GPIOs are 3.3V)
• Add 4.7K pull-up resistors on SDA and SCL lines if your PN532 breakout doesn't have them onboard
• Some PN532 boards need a brief delay after power-on before they respond on I2C

The rfidmodule setting in the config is for specifying which RFID hardware type to use, not for pin mapping. The pin mapping is done via i2cSDA and i2cSCL in brucePins.conf.