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# TCA9548

Arduino Library for TCA9548 I2C multiplexer.

## Description

Library for the TCA9548 and TCA9548a I2C multiplexer.
The library allows you to enable 0 to 7 I2C channels (ports) uniquely or simultaneously.
This is especially handy if you have multiple devices/sensors that have a fixed address.

**Warning**
The library is not tested extensively.

I2C address is 0x70 .. 0x77.

The library caches the channels enabled, and if a channel is enabled,
it will not be enabled again (low level) to optimize performance.

## Interface

### Constructor

- **TCA9548(const uint8_t deviceAddress, TwoWire \*wire = &Wire);)** Constructor, Address = 0x70 .. 0x77, wire = Wire or WireN.
- **bool begin(uint8_t sda, uint8_t scl, uint8_t mask = 0x00);**  Set I2C pins for ESP32 alikes, set mask of channels to be enabled.
- **bool begin(uint8_t mask = 0x00);**  set mask of channels to be enabled.
- **bool isConnected()** retuns true if address of the multiplexer itself is found on I2C bus.


### Find device

- **bool isConnected(uint8_t addr)** retuns true if arbitrary address is found on I2C bus.
This can be used to verify a certain device is available (or not) on an enabled channel.


### Channel functions

- **void enableChannel(uint8_t channel)** enables channel 0 .. 7. Multiple channels can be enabled in parallel.
- **void disableChannel(uint8_t channel)** disables channel 0 .. 7. Will not disable other channels.
- **void selectChannel(uint8_t channel)** enables a single channel 0 .. 7 uniquely. All other channels will be disabled, although these can be set again with enableChannel.
- **bool isEnabled(uint8_t channel)** returns true is a channel is enabled.
- **void setChannelMask(uint8_t mask)** enables 0 or more channels simultaneously with a bitmask.
- **uint8_t getChannelMask()** reads back the bitmask of the channels enabled.
- **void setResetPin(uint8_t resetPin)** sets the pin to reset the chip. (Not tested)
- **void reset()** trigger the reset pin.
- **getError()** returns the last I2C error.


## Operation

See example


## Future

- test test and test
- write unit test
- forced write to chip ? robustness vs performance
- set an "always enabled" mask  (have to investigate the consequences)