AVR-Chat

You need to.keep a var with the old output state just before you turned
them off. Then restore that before moving.
On Apr 28, 2013 10:50 AM, "Bernie" <berniemcintosh@yahoo.es> wrote:

> Hi,
>
> I have implemented a project using an ATMega328 to drive a stepper motor.
> Once the motor has reached the position required, I don't need it to move
> any more for say, 10 minutes at a time.
>
> The motor is taking current 100% of the time of course.
>
> I'd like to turn the power to the motor off, then the next time I need to
> move the load, start it up again without having lost the position
> information.  Holding torque is not a concern.
>
> I've tried this using the simple means of bringing the four outputs from
> the AVR low. When it comes to step the motor again, the first few pulses do
> not have any effect on the motor, so I lose steps and now don't know where
> the motor is - necessitating a reset cycle to bring it back to a limit
> switch.
>
> On making that first step after its been switch off, I've tried every
> possible beginning step sequence but can't get the right result.
>
> I'm coming to the conslusion that it can't be done. If you want to keep
> position intact, then don't turn off the outputs. If you do turn off the
> outputs you have to find its position again by sending it off to the limit
> switch.
>
> There may be other approaches by using more sophisticated hardware but at
> the moment the question relates to using this simple means of control as it
> has the lowest component costs.
>
> I'd be grateful if anyone here could comment. Apologies if its more a
> stepper question than an AVR question but I'm thinking that its relevant to
> many AVR users.
>
> Regards
>
> Bernie McIntosh
>
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> ------------------------------------
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