I am using the G2 24v13 motor driver with a Maxon DCX 14L DC motor. I want to control the torque of this motor by using the current feedback from the CS pin of the motor driver. According to the spec sheet, the relationship between the motor current and the CS output is 50mV + 40mV/A, meaning the offset is 50mV.
However, when I measured the CS output using a Teensy board (with Arduino analogRead, resolution set to 2^13 = 8192), I found that one CS pin output is 2.4mV and the other is 8.5mV. I used two motors and two G2 24v13 motor drivers.
I am surprised and confused because the same motor driver’s CS offset is different for each one, and these values (2.4mV and 8.5mV) are far from the 50mV specified in the datasheet.
We have a few products that have G2 24v13 in the name, but it sounds like you’re referring to the G2 High-Power Motor Driver 24v13. If that’s the case, while the typical offset is listed as 50mV, it can vary widely from unit to unit. For more accurate current sensing, I generally recommend having your program calibrate the offset automatically each time it is powered up (i.e. take an average of several measurements while the duty cycle is 0%).
It can be anywhere between 32 mV/A and 48 mV/A, so you might consider characterizing the specific units you’re using with a known current draw (e.g. using something like a power resistor or a bench-top electronic load).
By the way, if you have trouble getting the accuracy you want with the driver’s built-in current sense feature, you could also try using a separate current sensor.
