Now, this one is bloody amazing. Again, something I have been searching for for years.
How to make a HARDWARE Altimeter with the dual needles ? - or, any instrument with dual concentric action.
Most of the hardware users will probably know the X27 type stepper motors - the kind used in most automotive dash boards. These are capable of limited rotation or can be set for continuous with a simple snip of a lock tab inside the stepper.
Anyway - if you need more info on the X27 type stepper then just ask.
So, to make an altimeter you need two needles, concentric. Example - One for the 'feet' and one for the '1000 feet'
How about a simple stepper that combines - actually - two steppers with dual concentric operation ! ?? - wouldn't that be amazing ?
Well, I give you this .
https://www.aliexpress.com/item/1005001 ... 4c4df9iRIO
It looks like this -
Which is basically two X27 type steppers in one unit attached to a dual concentric shaft - bloody amazing.
You can drive both units from a simple AX1201728SG or VID66-06 IC (cheap as chips from Aliexpress) these 28 pin units can drive 4 X27 type steppers.
Yes, you MAY have to arrange some kind of calibration, but that is not overly difficult.
You may need a SOP to DIP converter (28 way) - but these are only a couple of euro for 10. !
AM says it supports the VID66-6 directly, but, this is VERY VERY misleading as it also, by the same definition - supports ALL the major industry standard stepper controllers that use DIR and STEP as the actual driver controls. - Hence - AM is rather misleading in this area and really needs to change the VID66 speciality definition to generic DIR / STEP controllers - of which there are many.. in fact, every industrial controller, or indeed, hobby stepper driver controller uses the exact same DIR / STEP control. Labelling it as VID66 in AM is very blinkered IMHO.
Anyway. What a superb unit
I am also working on a unit for driving 4 'normal' bipolar' stepper motors from the 28BYJ to the nema 17/ 23 units using A4988 drives with a CNC V3 shield for the uno. This is dirt cheap. ! you can buy an UNO - WITH the shield, AND 4 stepper drivers for about 10 euros.
I have set this up via 'normal' AM (NOT message port)! and it works great.
An example of the complete setup is -
https://www.aliexpress.com/item/4000768 ... 4c4dBD589O
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AND this includes the bloody UNO !
Anyway, that is for a later date.
Note, the X27 does need a
DIFFERENT specific driver as it as virtual one off - ether the speciality ICs - AX1201728SG or VID66-06 - or direct port control from an arduino - but this is a special case.
BUT !
For 'normal' steppers. the CNC shield and A4988 drivers can control almost anything you want - they have up to 2 amps drive per winding, up to 30V control, current limiting - adjustable - and full control over microstepping, - Some possible uses may be - electric trim wheel control, auto throttles, artificial horizon units (replacing the gyros).. anything you want.
The unit was originally designed to control a complete CNC 3d printer unit. As said, it CAN be driven directly from AM.. more to follow on that
Again, these can be used DIRECTLY from AM with the correct code. (
NO message port required ! - normal AM control)
AND, after all the 4 stepper driver controls, you have available up to 6 analog (ADC) inputs and 3 PWM outputs, or - if you want - 9 general purpose pins to use as you want (some caveats apply but just think that you have nine pins to do with as you want) - AGAIN - all from AM directly. A lovely unit. Very flexible.
The 28BYJ units, modded from unipolar to bipolar (simple) have double the torque of the original unipolar units, so become a really useful unit also. The world is your crab - or was in an oyster ?
If you want to know how to mod the 28BYJ from (YUK !
) unipolar to the more common and better standard
Bipolar - 4 pin dual coils - instead of the (YUK ! 5 pin centre tapped coils that nobody ever uses ! ) then just ask. - hint, cut a single trace on the PCB behind the blue plastic cover,,,,,,,,,,,,,,, and then remove the red wire completely. Job sorted.
Joe
edit - added link to another of my posts with much more information regarding stepper motors and drivers in general. Including the BYJ units etc.
https://siminnovations.com/forums/viewt ... 459#p36459