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# HC4051

HC4051 is an Arduino library for a HC4051 1x8 channel multiplexer.


## Description

HC4051 is a library to control the CD74HC4051 8 channel
multiplexer / demultiplexer and compatible devices.

The HC4051 allows e.g one analog port read up to 8 different analog channels,
or one digital port to read the state of 8 buttons.


The channel selection is done with four select lines **A, B, C**

The device can be enabled/disabled by the enable line **INH**


#### Compatibles

to elaborate.


#### Related to 

- https://github.com/RobTillaart/HC4051  (1x8 mux)
- https://github.com/RobTillaart/HC4052  (2x8 mux)
- https://github.com/RobTillaart/HC4053  (3x2 mux)
- https://github.com/RobTillaart/HC4067  (1x16 mux)


## Hardware connection

Typical connection is to connect the four **select pins** to four IO Pins of your board.

The optional **enablePin (INH)** must be connected to GND if not used.
This way the device is continuous enabled.

Example multiplexing analog in.

```
        processor                      HC4051
     +-------------+              +-------------+
     |             |              |             |
     |           A |------------->| S0       Y0 |
     |           B |------------->| S1       Y1 |
     |           C |------------->| S2       Y2 |
     |             |              |          Y3 |
     |          E  |------------->| INH      Y4 |
     |             |              |          Y5 |
     |         A0  |<-------------| Y        Y6 |
     |             |              |          Y7 |
     |         GND |--------------| GND      Y8 |
     |             |              | VCC         |
     |             |              |             |
     +-------------+              +-------------+
```


## Interface

```cpp
#include "HC4051.h"
```

#### Core

- **HC4051(uint8_t A, uint8_t B, uint8_t C, uint8_t enablePin = 255)** constructor.
Set the three select pins and optional the enable pin.
If the enablePin == 255 it is considered not used.
- **void setChannel(uint8_t channel)** set the current channel.
Valid values 0..7, this value is not checked, only the lower 3 bits will be used.
- **uint8_t getChannel()** get current channel 0..7.


#### Enable

These functions work only if enablePin is set in the constructor.

- **void enable()** idem.
- **void disable()** idem.
- **bool isEnabled()** idem.
Also returns true if enablePin is not set.


## Future

- keep in sync with HC4067 et.al.