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# M62429

Arduino library for M62429 volume control IC.


## Description

#### M62429

This library is used to set the attenuation (volume) of the 
M62429 IC a.k.a. FM62429.

The communication needs a minimum delay of 1.6 microseconds. 
This is defined in the library in **M62429_CLOCK_DELAY** == 2
For AVR (UNO, slow device) it is defined as 0, as the digitalWrite
takes time enough. 

For faster processors this define can be overruled runtime by setting it 
before including "M62429.h" or by defining it as command line parameter.

#### M62429_RAW

The library also implements a M62429_RAW class which has a minimalistic interface.
 

## Interface M62429

The interface is straightforward

Use **\#include "M62429.h"**

- **void begin(uint8_t dataPin, uint8_t clockPin)** defines the clock and data pin.
One has to create one object per IC. 
- **int getVolume(uint8_t channel)** channel is 0, 1 or 2 (both). 
In the latter case the volume of channel 0 is used as volume of both channels.
See remark future section.
- **int setVolume(uint8_t channel, uint8_t volume)** 
  - channel = 0, 1, 2 = both
  - volume = 0 .. 255
  - Note: if system is muted, no changes are made.
- **int incr(uint8_t channel = 2)** increment volume (both channels is default) until max (255) is reached.
This is another way to set volume that is better suited for a rotary 
encoder or a \[+\] button.
  - Note: if system is muted, no changes are made.
- **int decr(uint8_t channel = 2)** decrement volume (both channels is default) until 0 is reached. 
  - Note: if system is muted, no changes are made.
- **int average()** averages the 2 channels to same = average level.  
Sort of set balance in the middle functionality.
  - Note: if system is muted, no changes are made.
- **void muteOn()** silences both channels but remembers the volume.
GetVolume() will return the 'saved' volume value.
- **void muteOff()** resets the volume per channel again.
- **bool isMuted()** returns the muted state. 

Note: the volume goes from 0..255 while the actual steps go from 0..87.
Therefore not every step in volume will make a "real" step (roughly 1 in 3).
This choice is made as the range 0..255 is more often used than the 0..87 range
and therefore better fits other sensors and devices.


#### Error codes

The functions **getVolume(), setVolume(), incr(), decr()** and **average()**
can return one of the  error codes.


| value | name                 | notes     |
|:-----:|:---------------------|:----------|
|   0   | M62429_OK            | no error  |
|  -1   | M62429_MUTED         | system is muted, use **muteOff()** |
|  -10  | M62429_CHANNEL_ERROR | channel must be 0, 1 or 2          |


## Operation

See examples



## Interface M62429_RAW

The interface is minimalistic. 
No parameter or other checks are made.

Use **\#include "M62429.h"**

- **void begin(uint8_t dataPin, uint8_t clockPin)** defines the clock and data pin.
One has to create one object per IC. 
- **int getAttn(uint8_t channel)** channel is 0, 1 or 2 (both). 
In the latter case the attenuation of channel 0 is used as attenuation of both channels.
- **void setAttn(uint8_t channel, uint8_t attn)** 
  - channel = 0, 1, 2 = both
  - attenuation = 0 .. 87


## Future

#### Mixer

- Control multiple M62429 IC's 
- One shared dataPin and clockPin per IC. 
- use a PCF8574 / PCF8575 as selector 
- would allow for 16 stereo or 32 mono channels. 
Runtime configuration mono / stereo would be cool.

```
  PCF8574 or PCF8575 is used as device selector
  AND port takes DATA and CLOCK to right M62429
  identical schema for all 8/16 ports

             PCF8575                 AND             M62429
           +---------+              +---+          +---------+
           |         |=======+======| & |==========| data    |
           |         |   +===|======|   |          |         |
   - I2C - |         |   |   |      +---+          |         |
           |         |   |   |                     |         |
           |         |   |   |      +---+          |         |
           |         |   |   +======| & |==========| clock   |
           |         |   |     +====|   |          |         |
           |         |   |     |    +---+          |         |
           +---------+   |     |                   +---------+
                         |     |
     DATA  ==============+     |
     CLOCK ====================+
```


#### Volume pan model

- model with one **volume(0..100%)** and one **balance(-100..100)** == **pan()**.  
- Also a **left()** and **right()** incremental balance might be added.

Does this model work better than 2 separate volume channels?


#### Other

- separate releaseNotes.md?
- change **getVolume(both)** to return max of the two channels?
  would be better.
- **min()** to reduce volume to minimum of both channels.
- create **setAttn(channel, attn)** and **getAttn()** for low level control.
  - needs cached attn values.

**wont**
- **muteOff()** should increase gradually.  takes too much blocking time.
- **Mute()** could be per channel, default = both / all.
would add a lot of extra testing. the user can implement a **setVOlume(chan, 0)**
- **mute50()** reduces levels with 50% (rounded down?).
  user can implement this **setVolume(chan, getVolume(chan)/2);**