Stepper motor clock

Using Arduino Project Guidance
#1

Hi I’m planning on building a real time ( time of day sort !)clock into an old car instrument panel for “garage art”
Using three small stepper motors .
I’m planning on TB6612FNG control boards.
Before I get my wallet out ...
My plan is to connect all the control boards input connections to ( say) pins 5,6,7,8 of a nano ,then multiplex the STBY ( standby) connection so I can effectively “address “ each motor in turn .
The control boards inputs are 200k ohm, so there is no “ fan out” problems for the Arduino.
Does this aspect sound reasonable ??

#2

I suspect if you disable a driver with the STBY line its motor will be free to turn - will that be a problem?

It may also be wise to experiment to see if the motor jumps to a different step position when the driver is re-enabled.

If you use stepper motor drivers that take step and direction inputs you will have enough I/O pins to treat each one completely separately.

…R

#3

Thanks , the motors will support the hands when not powered so that’s ok . I need to try the effect of turning them off/on - hasn’t considered that ( I was going to lay the board out while I wait for Chinese post)

The driver I’ve sourced needs 4 wires, not seen the two wire types .

#4

hammy:
The driver I’ve sourced needs 4 wires, not seen the two wire types .

The driver in your link is a DC motor driver. If your stepper motor draws less than 1.7 amps you could use a DRV8825 stepper motor driver. If less than about 1.4 amps you could use an A4988, though I suspect the difference in price is very small.

Post a link to the datasheet for your stepper motor.

...R
Stepper Motor Basics
Simple Stepper Code

#5
#6

The link in Reply #4 is for the driver. I was asking for a link to the datasheet for the motor so that I could recommend a suitable specialised stepper driver.

...R

#7

Sorry !
I don’ t have a data sheet for the motor, it’s from a ford Ka instrument cluster ( which I’m using , driving the hands as the clock) - I’d say very similar to the X-27 automotive types , 150ohm coils .

#8

hammy:
I do t have a data sheet for the motor, it’s from a ford Ka instrument cluster - I’d say very similar to the X-27 types , 150ohm coils .

I had been assuming you were using a much bigger motor (the size of a 28BYJ-48, for example). I have no experience with those little instrument stepper motors.

The TB6612 is probably OK - except that it needs so many I/O pins. As the step-rate will be very low you could uses a port-expander chip to give you more I/O pins for your nano.

...R

#9