Hi. two question for the group:
Is the notion of controlling steppers (not the current but the motion) with PWM valid? I think it is and looking for confirmation to plan a project (with limited time) but there are many senior members that categorically insist otherwise (that steppers can only be driven by individual steps and PWM can only be used to control the current) that it is hard to argue. Maybe I am completely missing something? Here is some supporting info:
If the first assumption is correct and some stepper drivers/controllers use PWM as input to control the motor, is it possible to still send a step (one at a time) to move a stepper. i.e. send 10 distinct steps that would create a ten step movement. So, basically, these would be also PWM signal but at a very very low Hz. The driver/controller inputs seem to support 0 to x Khz input and low end should be OK.
Is the notion of controlling steppers (not the current but the motion) with PWM valid? I think it is and looking for confirmation to plan a project (with limited time) but there are many senior members that categorically insist otherwise (that steppers can only be driven by individual steps and PWM can only be used to control the current) that it is hard to argue. Maybe I am completely missing something? Here is some supporting info:
- While there are many drivers that control current with PWM (PWM controlled current drivers such as DRV8825) PWM can also be used to provide pulses to the leads (oversimplifying the language) and this simply seems to make sense.
- The Sanyo STK672-110 chip has it in the name (Two-Phase Stepping Motor Driver (Square Wave Drive) and describes the input "clock" as "The input frequency range for the clock signal used for motor speed control is 0 to 25 kHz". this seems very explicit that the PWM is provided to control speed and not the current. There is simply no other pin that could provide a step. Unless I am completely missing something, how does one use this chip with step/dir? Here is the link again: **broken link removed**.
- Also, page 14 for the IB462H manual there is a description how waves are used to energize phases to drive the motor (not the amount of current). Again, this seems fairly explicit unless I am completely overlooking something. There is no other pin to provide input for step https://motion.schneider-electric.com/downloads/manuals/discontinued_prod/ib462h.pdf
- Many videos online of people controlling speed of steppers with PWM. This could not be the case if the PWM only controlled the current and there were steps pulses sent to the motor on the side.
If the first assumption is correct and some stepper drivers/controllers use PWM as input to control the motor, is it possible to still send a step (one at a time) to move a stepper. i.e. send 10 distinct steps that would create a ten step movement. So, basically, these would be also PWM signal but at a very very low Hz. The driver/controller inputs seem to support 0 to x Khz input and low end should be OK.
- here is the supporting info from the Insturctables site: "In it's simplest form a PWM square wave can be created with a few lines of code. The following code would produce a signal with a 1 second Frequency and a 10% duty cycle. " https://www.instructables.com/id/Arduino-Hardware-PWM-for-stepper-motor-drives/
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