Stepper Motor Gauges

[mikeybear]

Hi .

I'm currently trying to build a couple of 3 needle gauges  using 3 stepper motors and have the prototypes working quite well.
The issue I still have to resolve , is zeroing them on startup , perhaps by using a photodetector .
Has anyone here solved this issue already ?

Thanks in advance

Dave

[mickc]

If they are continuous rotation steppers, then yes, you need to have a home position sensor.
Photosensors are a good option, I have also used hall effect sensors with micro neodymium magnets. 

[archen]

How do you make them calibrate on each startup? I mean software wise?



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[Atomic_Sheep]

How do you make them calibrate on each startup? I mean software wise?



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Rotate stepper until either a photo or magnetic switch is triggered. Place photo or magnetic switch where desired.

[mickc]

Yep, pretty much what Dimitry said.

Make the stepper move in one direction until the home sensor is activated (this is obviously the physical "0" position of the gauge) then set the position in the code to 0 steps.

This will depend on your hardware platform etc

[mikeybear]

Thanks Mick,

I think I'm going to investigate using hall effect , before photodetector, as I have very little space to play with.

Regards

Dave