While the Raspberry Pi Pico allows the I2C and SPI pins to appear in multiple locations, the u2if firmware fixes these locations to specific pins.

Power Pins

• VBUS - micro-USB input voltage
• VSYS - main system input voltage
• 3V3 - regulated 3.3V output, 300mA max
• GND - main ground reference
• AGND - ground reference for GP26-29 and ADC0 and ADC1

GPIO Pins

• GP0 to GP28 - General Purpose Input Output (GPIO) as well as Pulse Width Modulation (PWM)

I2C Pins

• SCL0 - I2C port 0 clock
• SDA0 - I2C port 0 data
• SCL1 - I2C port 1 clock
• SDA1 - IC2 port 1 data

SPI Pins

• SCLK0 - SPI port 0 clock
• MOSI0 - SPI port 0 data out
• MISO0 - SPI port 0 data in
• SCLK1 - SPI port 1 clock
• MOSI1 - SPI port 1 data out
• MISO1 - SPI port 1 data in

ADC Pins

• ADC0 - Analog to Digital Converter (ADC) 0
• ADC1 - Analog to Digital Converter (ADC) 1