The speed setting is 10.
That is what I calculated it would step if the coil pairs are mixed up. Every alternate step does not occur because the coil has the same voltage each side so no current flows.
The Motor Driver A+ A- must connect to same coil, same goes for B.
From your pics it looks like you have the pairs mixed up according to the datasheet I found.
Regards
Jim
This is the output of the Makerverse Motor Driver I assume.
What is the input, ie the Dir and PWM pins when you try running it again. PWM should always be high as the software sets it high and never changes it again.
If the input is there then the Motor Driver is the problem, it is going into shutdown like I said before or something else.
If the PWM pin goes low then the Motor Driver is being disabled. You would then need to figure out why.
All the best
Jim
Hi Jim, Jeff and Liam
Driver inputs measurements:
GP0 PwmPinA +3.2V
GP1 DiPinA 0V
GP2 PwmPinB +3.2V
GP3 DirPinB 0V
Driver output connections:
Resistance between B+ and B-, and A+ and A-: 3ohms approx
Resistance between B and A pins: many Megohms.
Results Summary:
Driver input OK
Driver output Connections OK
For reference the code being run is:
from Makerverse_Motor_2ch import bipolarStepper
from machine import Pin
from utime import sleep
onboard_LED = Pin(25)
onboard_LED.on()
stepper = bipolarStepper(pwmPinA=0, dirPinA=1, pwmPinB=2, dirPinB=3, RPM=10, stepsPerRotation=200)
stepper.rotate(50)
sleep(1)
print(“line 4”)
stepper.rotate(angle=-180)
print(“line 6”)
#stepper.returnHome()
onboard_LED.off()
print(“finish”)
Do you therefore think that there is something wrong with the MKVRS stepper motor driver board or is there something else I should test.
Cheers
Toni
Hi Toni
Under what conditions were these measurements taken.
are these resistance measurements made at the board connections or the stepper wires.
Was the stepper connected to the board.
Was the board powered. Resistance measurements should never be made with power applied.
Which way around were the meter leads
What type of meter (DMM or analog)
Without knowing a bit more about the actual measurement conditions these numbers don’t mean much although 3Ω seems low.
Cheers Bob
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@Toni135859
DirPinA & DirPinB pulse to step the motor. There is a 30ms delay between pulses. Calculated by 60000/(RPM*StepsPerRevolution). If you looked at it with an oscilloscope the pin would remain at one state for 60ms. DirPinA & DirPinB alternate. Using a multimeter it would be difficult to see the pulses.
3 ohms is very low. The NEMA-17 I have, measured 37ohms each coil.
The current through the Motor Driver may be over driving it at 3ohms, it could be going into thermal shutdown. The absolute maximum rating for the TC78H660FTG chip is 2A. At just 5V the rating would be exceeded if the coil resistance of each is only 3ohms.
I am looking at the Stepper Motor itself
The datasheet I found for the 17HS3417 lists the phase resistance as 1.9ohms. Matching close to what you have measured.
I think the Stepper Motor is not suited to this Motor Driver board.
Regards
Jim
Thanks to all your fantastic advice, clues, and many hours of testing etc I have changed the power supply from 12V (as I previously mentioned) to 5V and Eureka !!! It works as intended.
This may well be worth reinforcing in the Application Guide.
Toni
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Good to hear it now works.
At 12V and 3ohm coil resistance, it would be drawing a lot of current.
This is the Stepper Motor I have tried. Due to the higher coil resistance it works fine at 12V. 350mA is well within the capabilities of the Motor Driver chip.
Cheers
Jim
PS
The guide has a paragraph referencing current limiting. Maybe a WARNING could be added in bold or something. Up to Brenton what he wants to do.
Thanks again Jim I’ll keep that in mind
Cheers
Toni
Hi All
I think everybody, myself included, missed the “12V” part of this as most of the replies refer to 5V. At 12V and low winding resistance the current would indeed make that driver board sit up and think.
Anyway all good it is sorted even if it did take a month or so. Nothing is ever learned if it works first time.
Cheers Bob
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The learning point for me is the significant differences in coil resistance of Stepper Motors.
1.9 ohms to 30 ohms. You really need the motor specs to pick correct voltage and board.
My experience was with 12V and 37 ohm coil resistance, which worked fine with the board I was using.
So I assumed the one @Toni135859 was using was about the same.
Regards
Jim
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