Hi,
I was planning on using this breakout board to control two stepper motors for a school project. After reading its datasheet, I realized my whole life I've been treating servo motors and stepper motors as the same thing, since I only followed instructions and used libraries that exempted me from realizing their more detailed control.
I now understand the internal coils of a stepper motor cannot just be wired to PWM pin to run, and require a more advanced intermediary. My question is: do I have to buy a new shield with the PCA9865 chip and 'stepper drivers'? Or can I use the PCA9865, in conjunction with a couple h-bridges, to control the output angle of my steppers?
Stepper motors need drivers that controls the current. Drop this PCA9865!
Hi,
I could use a stepper motor driver like an A4988 in conjuction with the shield though?
This board is only capable of generating PWM signals. You cannot use it in conjunction with a stepper motor. The A4988 has to be connected directly to the Arduino.
Or did you mean using a A4988 to drive a stepper, and parallel the board to drive a servo ? That would be possible.
I use A4988 for reasonable steppers using a max of 1.5 Amp, heatsinked and forced cooling by a fan. I use a PROOTOONER V3 board. There are also the TB6500 or TB6600 for more current.
Post a link to the steppers!
Hi,
I meant using a microcontroller to A4988 (after doing some more reading I'm thinking a DRV8825 stepper driver actually) which then interfaces with the steppers. But it would be in parallel? I thought the control flow would be: microcontroller sends square wave with a certain duty cycle -> DRV8825 uses two h bridges to move the motor? Or is my brain mush due to treating these like servos for so long? Do I not need the PCA9865?
Cool! I found these stepper drivers which have heat sinks and are thus rated for 2.2 A, which I think will work better for my stepper motors - I'm using 17HS4401 steppers, which should draw 1.7 A (from what I read on the datasheet).
That sounds better. Drop all ideas about H bridges and steppers. H bridges are for DC motors...
Not to drive the stepper.
Well, it indeed contains to H-bridges to drive the motor coils. But it contains much more to control these bridges in the right way. It's not a simple H-bridge - it controls the current flow through the coils.
The microcontroller must provide one signal to define the direction of turning the motor, and one pulse signal to step it ( each pulse creates one step of the motor. There is no 'duty cycle'.
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