# I2C Constants

This page aggregates all I2C-related constants used by functions and methods from the C and C++ APIs.

MAX_I2C_TRANSFER_LENGTH

  Maximum I2C payload length in bytes per transfer request.

I2C_BUS_A

  Select I2C bus/channel A. For Pulsar, accessible through the I2C-dedicated Qwiic connector. For Supernova, it is accessible though both the I2C-dedicated Qwiic connector and the 2x15 pin connector.

I2C_BUS_B

  Select I2C bus/channel B. This bus id applies only for the Pulsar. This bus is accessible through the 2x15 pin connector and the external breakout board.

I2C_PULLUP_150Ohm

  Configure 150 Ohm pull-up resistance.

I2C_PULLUP_220Ohm

  Configure 220 Ohm pull-up resistance.

I2C_PULLUP_330Ohm

  Configure 330 Ohm pull-up resistance.

I2C_PULLUP_470Ohm

  Configure 470 Ohm pull-up resistance.

I2C_PULLUP_680Ohm

  Configure 680 Ohm pull-up resistance.

I2C_PULLUP_1kOhm

  Configure 1.0 kOhm pull-up resistance.

I2C_PULLUP_1_5kOhm

  Configure 1.5 kOhm pull-up resistance.

I2C_PULLUP_2_2kOhm

  Configure 2.2 kOhm pull-up resistance.

I2C_PULLUP_3_3kOhm

  Configure 3.3 kOhm pull-up resistance.

I2C_PULLUP_4kOhm

  Configure 4.0 kOhm pull-up resistance.

I2C_PULLUP_4_7kOhm

  Configure 4.7 kOhm pull-up resistance.

I2C_PULLUP_10kOhm

  Configure 10 kOhm pull-up resistance.

I2C_PULLUP_DISABLE

  Disable internal pull-up resistors.