I need to set the Vref to 675mV (90% of 1.5A motor Vref of 750mV) on a DRV8825 brake-out board, but can not because it’s not stable. It jumps from around 20mV to over 1V!!! I am using a 12VDC power supply for test purposes and will be using 24VDC on the final design.
Yes, I know the Vref pot is extremely sensitive and a very small rotation will cause a very large voltage change.
What could be causing this?
It isn’t obvious to me what might be causing that kind of problem from your description, but it might be something like a connection issue. Can you post some pictures of your setup showing all of your connections, as well as some close-up pictures of both sides of the DRV8825 carrier board?
OK, here are the pictures you asked for.
From your pictures, it looks like the DRV8825 carrier you are using is a knockoff and not manufactured by us. We cannot offer support for knockoff boards, but please note that they might perform differently from ours (e.g. the equation for setting the current limit might be different or there might be other differences in their connections).
If you want to try again with a genuine Pololu DRV8825 carrier, you can order one directly from our website or from one of our official distributors.
I want to use your board but it is out of stock. Is there any word when it will be back in stock? I bought this one on eBay. I only need one for testing.
I checked your list of distributors, and they are all out of stock.
We are currently able to make a small quantity of those within about a week if you backorder them now. Alternatively, you might consider one of our MP6500 or TB67S249FTG carriers.
By the way, please note that the forum is generally not a good place to ask stock and lead time questions, so please email us if you have more questions like this.