GY-63_MS5611/libraries/AnalogKeypad/README.md

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# AnalogKeypad

Library for (Robotdyn) 4x4 and 4x3 analog keypad.


## Description

AnalogKeypad is a simple library to read the keys from a (Robotdyn) 4x4 or 4x3 keypad.
No other keypads are tested, but they should work with this library after adjusting
the **MAGIC NUMBERS** in the function **rawRead()**.


#### Related

- https://github.com/RobTillaart/I2CKeyPad
- https://github.com/RobTillaart/I2CKeyPad8x8


## Interface

```cpp
#include "AnalogKeypad.h"
```


#### Constructor

- **AnalogKeypad(const uint8_t pin, const uint8_t bits = 10)** constructor, pin is typical A0 etc.
Bits has a default of 10, but need to be set to match the platform.
If bits < 8 then the internal shift would be large causing all reads to return 0 or so.


#### polling interface

- **uint8_t pressed()** returns 0 if no key pressed, otherwise returns key pressed (may fluctuate).
- **uint8_t read()** read the key pressed returns 0 .. 16 where 0 means NOKEY.


#### event interface

- **uint8_t event()** checks if a change has occurred since last time.
- **uint8_t key()** returns the key involved with last event.

```cpp
  uint8_t e = AKP.event();
  switch (e)
  {
    case PRESSED:
      Serial.print("press\t");
      Serial.println(AKP.key());
      break;
    case RELEASED:
      Serial.print("release\t");
      Serial.println(AKP.key());
      break;
    case REPEATED:
      Serial.print("repeat\t");
      Serial.println(AKP.key());
      break;
    case CHANGED:
      Serial.print("change\t");
      Serial.println(AKP.key());
      break;
    default:  //  NOKEY
      break;
  }
```

|  Event     |  value  |
|:----------:|:-------:|
|  PRESSED   |   0x80  |
|  RELEASED  |   0x40  |
|  REPEATED  |   0x20  |
|  CHANGED   |   0x10  |
|  NOKEY     |   0x00  |


## Operation

The simplest usage is to use the **read()** function.
This will return a 0 (NOKEY) when no key is pressed and
a number 1 to 16 for the keys pressed. Note the return value may
fluctuate randomly when multiple keys are pressed.

The **pressed()** function is a bit more robust.
It returns the key pressed first, so multiple key presses simultaneously
are less likely to disturb your program.

See Examples


## Future

#### Must

#### Should

- more examples
  - self-learning example?

#### Could

- make internal mapping array runtime adaptable?
  - store in RAM, accessor functions
- version for external ADC
  - see ADC712

#### Wont