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# MAX14661

Arduino library for MAX14661 multiplexer with I2C interface.


## Description

The MAX14661 multiplexer is a 16x2 channel multiplexer. 
It has 2 lines A and B which can be 
connected up to 16 A lines and 16 B lines.

The device can be controlled by SPI or I2C. 
This library implements only an I2C interface


## Interface

The library provides 3 kinds of interfaces. 
Mixing these interfaces is allowed but definitely not advised as 
especially the PAIR interface assumes that A and B selections 
are kept in sync.

So depending on your application choose the interface you want to use.


### Constructor

- **MAX14661(deviceAddress, TwoWire \*wire = &Wire)** Constructor with device address, 
and optional the Wire interface as parameter.
- **bool begin()** initializes the wire interface 
- **bool begin(sda, scl)** idem, for the ESP32 where one can choose the I2C pins.
- **bool isConnected()** checks if the address is visable on the I2C bus


### PAIR interface

The functions in this interface part all work symmetrical on the A and B line. They are managed as a PAIR. So this is ideal e.g. to multiplex an I2C bus.

The interface allows to have multiple lines A/B open in parallel.

  // open ==> connect
- **bool openChannel(uint8_t channel)** connects A/B to output channel
- **bool closeChannel(uint8_t channel)** disconnects channel from A/B
- **bool isOpenChannel(uint8_t channel)** returns true if connected to A/B
- **void openAllChannels()** connects all channels
- **void closeAllChannels()** disconnects all channels
- **void setChannels(uint16_t mask)** connect multiple channels with a bit mask.
- **uint16_t getChannels()** returns a bit mask of the channels connected.


### SHADOW interface

not implemented yet. 

Allows to prepare which channels should be selected and set them all at once. 



### MUX interface

The MUX interface allows one channel to be open at a time.

- **void MUXA(uint8_t channel)** if channel < 16 only that channel will be selected. All other values will select no channel.
- **uint8_t  getMUXA()** returns the selected channel. 255 means none selected.
- **void MUXB(uint8_t channel)** if channel < 16 only that channel will be selected. All other values will select no channel.
- **uint8_t getMUXB()** returns the selected channel. 255 means none selected.


### FULL CONTROL interface

full control per channel, any combination is possible.
Use with care as these can interfere e.g. with the PAIR interface.
All functions return false if channel > 15.

- **bool openA(uint8_t channel)** idem
- **bool openB(uint8_t channel)** idem
- **bool closeA(uint8_t channel)** idem
- **bool closeB(uint8_t channel)** idem


### LOW LEVEL CONTROL interface

Check datasheet for these values of the registers.

- **uint8_t readRegister(uint8_t reg)** read low level device register.
- **int writeRegister(uint8_t reg, uint8_t value)** write value to device register.


### Misc

- **lastError()** returns the last error, limited to I2C for now.


## Error codes

to be elaborated


## TODO

- test test 
- write unit tests.
- SHADOW interface
- error handling
- improve documentation
- initial value param for begin()?


## Operation

See examples