Hi all,
I have a few drv8833 carrier boards from pololu and I am wondering what would be the best way to either sense the current with a microcontroller, or dynamically limit current from the micro. In other words, I don’t just want to hookup a fixed resistor to a/bisen and have a fixed current limit. I want to be able to dynamically limit torque. If I can sense current I can do it in code, or if there is a device I can hookup to a/bisen pins to set the current limit from the micro. Hopefully a cheap/easy solution, would be nice. Thanks for all ideas.
Josh
Hello.
We do not have a straightforward way to get dynamic current limiting with our brushed DC motor drivers. Instead of using resistors with a fixed value, you might consider adding a digital potentiometer to the DRV8833, so that you could control its resistance from your microcontroller. You might also consider adding an external current sensor to monitor that current draw. The ACS714 Current Sensor Carrier -5A to +5A measures the smallest amounts of current among our selection of current sensors, but I do not expect it to have a low enough sensitivity to achieve fine current limiting control for the kinds of low currents a DRV8833 can handle. We do not have any specific recommendations on where you could find an appropriate pot or current sensor for this kind of thing.
-Jon
Thanks for the ideas. I thought about using a digital pot. That would be ideal. But I couldn’t find one with low resistances. Does anyone have any experience using one for this purpose? From what I can tell from the data sheet, the resistance would need to be real low, on the order of 1 ohm. Another idea would be to make my own digital pot using a few fixed resistor values and some reed switches or something in a ladder config. Any thoughts appreciated.
Josh
