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Author Topic: Motorshield alternative?
SnyperBob
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Posts: 42
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Post Re: Motorshield alternative?
on: March 14, 2012, 21:44
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Thanks for posting up those docs!
sandy
Administrator
Posts: 1317
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sandy
Post Re: Motorshield alternative?
on: March 14, 2012, 22:00
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I am sure there will be a couple of things to keep an eye out for, but that's good news. You can edit the lines in the setup() method

  digitalWrite(motoraMicrostep1, LOW);
  digitalWrite(motoraMicrostep2, LOW);

to enable microstepping - each combination of LOW or HIGH here sets a different size (the little table of combinations is in the pdf you posted).

Your servo signal connection is still present on pin 10, but you'll need to pipe in GND and +5v from elsewhere on the board - should still work.

(now, where's mine!?)
sn
woodpecker
Beginner
Posts: 33
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Post Re: Motorshield alternative?
on: March 15, 2012, 09:53
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Thank you sandy, yours will arrive soon, im sure. mine was shipped inside the country thats why it was here so fast.
sandy
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Posts: 1317
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sandy
Post Re: Motorshield alternative?
on: March 15, 2012, 14:02
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I think the servo might be trickier. It looks like the motorshield helpfully breaks out the analog pins alongside GNDs and +5Vs (labelled "elec brick" or somesuch), but these aren't the pins that the current Servo library targets.

There is a softservo library knocking around, so I might try that - it works a bit differently so will need looking at, but the servo application is pretty crude anyway, so I don't think it'll be a problem.

sn
sandy
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Posts: 1317
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sandy
Post Re: Motorshield alternative?
on: March 16, 2012, 23:26
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Got it - neat shield and working great so far for tests. I've updated the repo.

Two changes:

1. I've taken out the explicit microstepping settings, this means that those settings will be controlled with the jumpers on the board instead of through software.

2. The other thing is to move the pen lift servo onto pin D16 (aka A0), which is the first of the block of 3pin headers on the board. Plug the servo in with the signal lead (the white one) on the "s" row of pins.

Sure gets hot, and I don't see a way to "freewheel" at first glance (cut the power), so that's a bit of a impediment. On the other hand, it's got good connectors - 4 pin headers as well as screw terminals for the motor connections: Nice job. And a switch to choose between 5v and 3.3v

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