This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

What this library is

I2C_device_Arduino is an Arduino library providing a base abstraction class (I2C_device) for I²C device register-level access. Other NXP Arduino libraries (GPIO, LED driver, RTC, temp sensor, etc.) depend on this as a base class.

The library also includes optional SPI support via txrx(), allowing subclasses to override register access for SPI-connected devices.

Key source files

src/I2C_device.h / src/I2C_device.cpp — the main abstraction class
src/test_LM75B.h / src/test_LM75B.cpp — example subclass for LM75B temperature sensor (shows how to derive from I2C_device)

Generating documentation

doxygen Doxyfile

Output goes to docs/. The generated HTML is published via GitHub Pages.

After editing Doxyfile, run doxygen -u Doxyfile to migrate obsolete tags before committing.

API conventions

All register-access methods (reg_r, reg_w, read_r8, etc.) accept a bool stop parameter that controls whether a STOP condition is issued after the transaction. Default is true. Set to false to use REPEATED-START between write and read (needed for some devices).
rs_dis (repeated-start disable) is the internal inverse flag; repeated_start_enable(bool) sets it.
bit_op8 / bit_op16 perform read-modify-write on a register using a mask.
Static methods ping(addr) and scan(wire, stop) do not require a device instance.

Branch naming

Active branch 1-register-bits-overwriting-operation-may-need-to-be-done-without-stop-condition tracks work on making bit_op8/bit_op16 operate without an intermediate STOP condition between read and write.