Thank you, Allex, for your comments. When time permits, I will separate the
issues into different posts.
As a first step I have put code for two devices on Github:
- https://github.com/robvanlopik/PCA9685-PWMExpander
- https://github.com/robvanlopik/DS1307-TinyRTC
While working on the PWM module, it occurred to me that PharoThings has two
different points of view. The first I would call "board-centric", where we
tell the board what to do with its pins. That is also the way my
PotPCA9685Device works. On the other hand there is the "pin-centric" view
where pins have functions and are told what to do. This view is used in the
inspectors. As the outputs of the PCA9685 look very much like GPIO pins, I
wondered whether it would be worthwhile to model them as such. This doesn't
seem possible in a direct way, so it would need the introduction of a
PotBoardExpander. Maybe PotBoardConnector could be adapted for this
purpose, but I think it should be something different.
This reasoning also stems from my feeling that the Arduino is not really a
PotBoard. For one thing, there is no reason why it would have to be a
singleton; I can attach Arduinos through numerous serial and USB ports (and
Bluetooth). On the other hand it would very well fit the description of a
PotBoardExpander. In that case PotBoard should have a superclass
PotController that allows for having no pins of its own.. so any computer
can control one or more Arduinos (To be precise, by "Arduino" I mean a
Arduino-like board running the Firmata sketch and communicating through the
Firmata protocol).
The reason one would want to do this, is to have a uniform way of
controlling pins, irrespective of board or device. Maybe this uniformity
can also be achieved by implementing the protocol of PotBoardDriver for any
device that has GPIO-like pins.
I have not been able to find a description of the design of PharoThings,
but maybe someone wants to comment on these thoughts.
In the meantime I will start looking at Firmata.
cheers,
Rob van Lopik
