How do I use the LTE expansion board I2C in Arduino?

I am in charge of SPRESENSE support for Sony.

Added a Wire1 instance to the Wire library to take advantage of I2C #1 (shared pins with PWM2,3) from the Spresense Arduino environment.

Pin compatibility is as follows: I/O voltage can be switched between 3.3V/5V depending on the jumper on the expansion board side.
PWM2:I2C#1-SCL
PWM3:I2C#1-SDA

It is used in the same way as a typical Wire library.
Replace Wire.begin() with Wire1.begin().

"We have uploaded the corresponding items to the ""develop"" branch."
https://github.com/SPRESENSE/spresense-arduino-compatible/releases
SPRESENSE beta release (2021/09/11)

For instructions on how to use the Arduino package from the Development ("develop") branch, please refer here.
https://developer.sony.com/develop/spresense/doInstalling the cs/arduino_set_up_ja.html#_Pre-Release_spresense_arduino_board_package_Package

We plan to incorporate this response into the next official release and officially support it will be officially supported.

Thank you for your continued support on SPRESENSE.
SPRESENSE Support Team