I2C channel-select decorator for the TCA9548A / PCA9548A. More...

#include <TCA9548AInterface.h>

Inheritance diagram for TCA9548AInterface:

Public Member Functions
	TCA9548AInterface (I2CInterface *bus, uint8_t muxAddr, uint8_t channel)

void	begin () override
	Initialise the underlying bus and invalidate this mux's channel cache.

void	writeRegister (uint8_t devAddr, uint8_t reg, uint8_t val) override
	Activate this channel (if not already selected), then forward the write.

Public Member Functions inherited from I2CInterface
virtual	~I2CInterface ()

virtual void	writeByte (uint8_t addr, uint8_t data)
	Write a single data byte to a device (no register address byte).

Detailed Description

I2C channel-select decorator for the TCA9548A / PCA9548A.

writeRegister() selects this instance's channel on the mux (if not already selected) then forwards the write to the underlying bus. The matrix and driver layers are completely unaware of the multiplexer.

Channel state is cached per mux address in a function-local static array (8 bytes of BSS). Calling begin() invalidates the cache entry for this mux so the first subsequent write always emits the channel-select byte.

Constructor & Destructor Documentation

◆ TCA9548AInterface()

TCA9548AInterface::TCA9548AInterface	(	I2CInterface *	bus,
		uint8_t	muxAddr,
		uint8_t	channel
	)

inline

Parameters

[in]	bus	Physical I2C bus; must outlive this object.
[in]	muxAddr	TCA9548A 7-bit address (0x70–0x77).
[in]	channel	Bus segment to activate on writeRegister() (0–7).

Member Function Documentation

◆ begin()

void TCA9548AInterface::begin ( )

inlineoverridevirtual

Initialise the underlying bus and invalidate this mux's channel cache.

Call once per mux address in setup() before any matrix.begin() calls. Invalidating the cache guarantees the channel-select byte is sent on the very first writeRegister() even if that channel was previously active.

Reimplemented from I2CInterface.

◆ writeRegister()

void TCA9548AInterface::writeRegister	(	uint8_t	devAddr,
		uint8_t	reg,
		uint8_t	val
	)

inlineoverridevirtual

Activate this channel (if not already selected), then forward the write.

When the channel is already active the mux write is suppressed entirely — zero overhead compared to a direct I2C connection.