Update Stepper to wrap AccelStepper

[soundanalogous]

I'm open to completely rethinking the interface. To avoid breaking existing client support we should use a different command byte (I'm proposing 0x62) and deprecate the old version (0x72). Since this will be a wrapper library (wrapping AccelStepper) it should be created in a separate repo in the same format as FirmataEncoder. I will need to rename FirmataStepper in the utility folder to allow the wrapper library to be named FirmataStepper. StepperFirmata will then be deprecated.

Start with the updated protocol: firmata/protocol#42

[soundanalogous]

Consider the requests from #26 and #2

[DomAmato]

what features do we all want to wrap? Also I think this is the most recent revision here:
https://github.com/d235j/AccelStepper
though I don't know if that is the dev repo
That one should be up to date with this
http://www.airspayce.com/mikem/arduino/AccelStepper/

[DomAmato]

Looking over the header class it seems we should aim for

• A config/constructor
• move absolute
• move relative
• set Acceleration
• Set Speed

Maybe

• set a max speed
• distance to go
• target position
• current position
• disable outputs
• enable outputs
• set min pulse width <- probably will never get called fast enough
• set enable pin <- not super sure what this does
• set pins inverted

We can't do

• run to position <- a blocking function
• run speed to position <- a blocking function
• run to new postion <- a blocking function

[soundanalogous]

One way to start would be to define the ideal stepper interface regardless of what is wrapped. You had some proposals for the protocol a while back so that could be a place to start and solicit feedback.

[soundanalogous]

We could start by breaking out the proposed commands from here into a list. Maybe do that here: firmata/protocol#42. No need to work out all the details of the protocol yet, just get a list started and then see if others have any feedback. I can bring it to the attention of some people in the nodebots community as there may be some opinions there.

[dtex]

Finally found some time to work on this and am making good progress. I'm finding however that I'm limited in the number of steps I can make per second. Is the frequency of calls to loop() just dependent on what the hardware will allow or is there a predetermined interval?

I'm maxing out around 450 steps/sec right now.

[soundanalogous]

It depends on the clock speed and the amount of work being done in the loop. There is no way I know of to make it faster other than running on a faster microcontroller and making sure you don't include unneeded Firmata features.