[PD] Arduino Mega + Pduino

[Hans-Christoph Steiner]

FYI: Paul Stoffregen is working on full Arduino Mega support for  
Firmata/Pduino.  I know some people onthis list were interested in  
that.  He's looking for testers now, the code is here:

http://www.pjrc.com/tmp/firmata/

Once its tested, we'll work on integrating it into the regular Firmata  
releases.

.hc


Begin forwarded message:

> From: Paul Stoffregen <paul at pjrc.com>
> Date: January 5, 2010 10:12:55 AM EST
> To: firmata-devel at lists.sourceforge.net, Hans-Christoph Steiner <hans at at.or.at 
> >
> Subject: better hardware abstraction
> User-Agent: Thunderbird 2.0.0.23 (X11/20090817)
>
> I just uploaded a copy of StandardFirmata using what I believe will  
> be much better hardware abstraction.
>
> http://www.pjrc.com/tmp/firmata/
>
> The concept is use two sets of macros, IS_PIN_xxx() to test if any  
> particular pin supports a feature, and PIN_TO_xxx() to translate  
> firmata pin numbers (as used in the protocol) to actual numbers used  
> by the hardware functions.
>
> Often these macros are very simple.  But when a translation is  
> needed, they can.  For example, on a standard Arduino, for digital  
> pins the macros are:
>
> #define IS_PIN_DIGITAL(p)       (((p) >= 2 && (p) <= 13) || ((p) >=  
> 16 && (p) <= 21))
> #define PIN_TO_DIGITAL(p)       (((p) < 16) ? (p) : (p) - 2)
>
> Pins 14 and 15 are not implemented, and pins 0 and 1 are not  
> available for digital I/O due to being used for Rx and Tx.  The  
> PIN_PIN_DIGITAL() macro lets StandardFirmata easily adapt.  The  
> PIN_TO_DIGITAL() macro is used whenever calling pinMode,  
> digitalWrite, digitalRead (but optimized 8 bit port access has to be  
> special coded).  For a standard Arduino, when the analog pins are  
> used as digital I/O, this macro makes sure pinMode gets called  
> correctly.  Even though it's pin 16 as presented by Firmata,  
> Arduino's pinMode function expected 14 to map to the first analog  
> input.
>
> The core concept behind this abstraction layer is every "firmata  
> pin" may support any number of features which are checked with  
> IS_PIN_xxx(), and if the feature is available, PIN_TO_xxx()  
> translates the "firmata pin" into a "hardware pin".  Everything in  
> StandardFirmata works based on "firmata pins" and then checks and  
> translation into "hardware pins" are used when actually performing I/ 
> O.
>
> This simplifies the StandardFirmata code in many places.  In the  
> long run, I believe this approach will be much more maintainable,  
> since it tends to make the code more readable.  As more pin features  
> are added, this scheme is simple to extend.
>
> As promised, I've done quite a bit more testing.  I modified Pduino  
> to work with more pins and did quite a lot of testing on Arduino  
> Mega (on 0017, there is a known bug with analog inputs 8 to 15, so  
> be sure to patch your wiring_analog.c file, if you haven't  
> already).  I haven't tested everything in every possible way, but  
> this does seem to be working quite well.
>
> I realize this is a pretty substantial change.  I hope you'll  
> consider it.
>
>
> -Paul
>
>
>
>
>
>



----------------------------------------------------------------------------

Looking at things from a more basic level, you can come up with a more  
direct solution... It may sound small in theory, but it in practice,  
it can change entire economies.     - Amy Smith