Arduino-compatible TwoWire I2C controller/target interface. More...

Topics
	Wire Result Codes

Classes
class	TwoWire
	Arduino Wire-compatible I2C controller/target interface. More...

class	TwoWireObject
	Convenience wrapper binding a TwoWire instance and device address. More...

Typedefs
typedef void	slave_rx_handler(int num_rx)
	Callback type for target (slave) receive events.

typedef void	slave_rq_handler()
	Callback type for target (slave) request events.

Variables
class TwoWire	Wire
	Pre-declared global TwoWire instance using platform default pins.

Detailed Description

Arduino-compatible TwoWire I2C controller/target interface.

#include< Wire.h>

The Wire interface provides an Arduino-compatible API for communicating with I2C devices using the TwoWire class. It supports both hardware I2C peripherals and, when BBI2C is defined, a software bit-banged fallback for arbitrary pin pairs.

Key features:

Hardware I2C with automatic software (BBI2C) fallback
Controller (master) and target (slave) modes
Register convenience functions (readRegN(), writeRegN(), etc.)
Thread-safe operation using semaphore-based locking
TwoWireObject helper class for device-address-bound register access

Basic usage flow:

Construct: TwoWire Wire; or TwoWire Wire(sclPin, sdaPin);
Optionally set clock: Wire.setClock(400000);
Initialize: Wire.begin();
Transmit / request data
Shut down: Wire.end();

I2C Pin Mapping Reference

Each platform defines a valid_i2c[] table listing all supported SCL/SDA pin combinations and their associated hardware I2C modules. The parameterless TwoWire constructor selects the first entry (index 0) of this table.

If BBI2C is defined and the requested pins don't match any hardware entry, software bit-banged I2C is used automatically.

For full per-platform pin tables see examples/TwoWire_I2C_Pin_Reference.md.

Quick Reference — Default Pins Per Platform

Platform	CPU	Default SCL	Default SDA	I2C Module
SOMRT1061	i.MX RT1061	Pins[9] (EMC_12)	Pins[10] (EMC_11)	LPI2C4
MODM7AE70	SAME70	P2[42] (PA4)	P2[39] (PA3)	TWIHS0
MOD5441X	MCF5441X	J2[42]	J2[39]	I2C0
NANO54415	MCF5441X	Pins[22]	Pins[20]	I2C1
SB800EX	MCF5441X	Pins[5]	Pins[4]	I2C4

See examples in your NNDK under examples/I2C/Wire

Typedef Documentation

◆ slave_rq_handler

typedef void slave_rq_handler()

#include <Wire.h>

Callback type for target (slave) request events.

Called when the controller requests data from this device. The handler should call TwoWire::write() to queue response bytes.

◆ slave_rx_handler

typedef void slave_rx_handler(int num_rx)

#include <Wire.h>

Callback type for target (slave) receive events.

Parameters

num_rx Number of bytes received from the controller

Topics

Classes

Typedefs