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Driver Does not respond to pulses

Posted: Thu Jun 10, 2021 2:51 am
by JAGADISH K
Hi,
I'm using CVD223-K 2 phase stepper motor driver with a 2 phase Oriental stepper motor. I tried to interface the driver's Direction pins i.e. CW and CCW with a PSOC MCU's GPIO. The driver's DIP switch settings were as follows,
  • 2 pulse mode enabled
  • Smooth Drive ON
  • Rest of the switches are towards OFF position
The below picture shows the wiring diagram since I can't implement a Line driver on PSOC MCU I opted for OPEN COLLECTOR TYPE IO interface
Oriental.png
Oriental.png (57.18 KiB) Viewed 40 times
5V from the board which houses PSOC MCU was connected to pins 1,3,7 of the driver's CN3 connector and AWO was not connected.
The MCU does a homing sequence wherein the motor rotates clockwise until the limit switch is closed and rotates in a counter-clockwise direction until the limit switch is opened. During the course of the evaluation of the driver, I ran into some issues, like I can't do homing twice, it would perform one homing position and stall. Upon further debugging, I found out when the Command filter DIP switch is turned ON this issue was resolved. When I put homing in a while loop so it executes indefinitely I noticed something, the first homing has proper movement but the subsequent homing is totally different. The video in the link shows what I have described, first homing movement is the desired one but the rest of homing movements are small movements, I had reset the MCU a couple of times to make this observation evident.
The PWM frequency used is 1KHz (300RPM) and the duty cycle is 50%.
In code first I disable Microstepping, feed pulses to appropriate pin and stop PWM then feed different pin with the PWM pulses for opposite direction rotation.
My question is what are the sequences that I must follow when driving these pins with regards to pin drive mode, whether when driving CW pin should the CCW put to high impedance and why the above "homing repeatedly" command renders incorrect homing movement except for the first iteration which is the desired one.
Since this drive mechanism is going to be used in a Medical device these kinds of behaviors cannot be present, if anyone could shed some light on this issue it would be great.
Thanks in Advance

Re: Driver Does not respond to pulses

Posted: Thu Jun 10, 2021 9:05 am
by om_tech_support_KR
Hello,

When running in 2 pulse mode with the CW input the CCW input should be off and if switching directions there should be a 5 us or more delay between signals. This can be referenced on the timing chart on page 12 of the link below. To verify if driver is receiving correct pulse its best to measure pulses with an oscilloscope. Another parameter to check is the max starting frequency capability of the motor being used. You can try lowering the starting frequency then ramping up to speed to see if this helps.

https://www.orientalmotor.com/products/ ... df#page=12

Re: Driver Does not respond to pulses

Posted: Fri Jun 11, 2021 12:31 am
by JAGADISH K
Hi,

I'm giving a one-second delay before feeding pulses to different direction pin even then, same behavior is exhibited. The Motor used is PKP245D23B2 and the start frequency for it is well above 300RPM which is what I'm using by feeding 1KHz pulses.

Re: Driver Does not respond to pulses

Posted: Fri Jun 11, 2021 7:58 am
by om_tech_support_KR
Hello,

It's recommended to use an oscilloscope to check the pulses going to the CW and CCW pins on the driver to see if correct voltage levels are being observed. The voltage levels of pulse signals are on page 10 of the driver manual.

https://www.orientalmotor.com/products/ ... df#page=10