Pololu Robotics & Electronics
Menu
My account Comments or questions? About Pololu Contact Ordering information Distributors

Pololu Forum

G2 24v21 motor driver CS pin output always 0.05

I purchased G2 24v21 motor driver recently and had it worked with my motor. However, I cannot read any value other than 0.05 (after converting using equation measured voltage = analogRead() value / 1024.0 x 5.0) both using analog pin of an Arduino or a multimeter. The motor driver is powered by a 16v battery and mounted a 470uF, 50V capacitor as required in the product page. It can be controlled without any problem by PWM signal from Arduino (both pro mini and mega). The PWM frequency is 20k Hz. I suppose when PWM signal has a 30% or 50% duty cycle, the H bridge should be active and therefore there should be some value sensed from CS pin on the motor driver. I connect PWM, CS, DIR, and GND pins to my Arduino and all other pins are left open. Can someone help me troubleshoot this situation? Thanks in advance.

Hello.

Can you post some pictures that show your board, connections, and the other components in your setup (like your motor and power supply)? How much current does your motor draw in your system?

-Patrick

Hi Patrick,

Thanks for your reply. Attached are pictures of my connections…

The connections from G2 motor driver to Arudino Pro Mini:
PWM --> D10
DIR --> D8
CS --> A1
GND --> GND

The motor will draw around 0.5A for a 60% duty cycle PWM. Also, I added a 100k omh resistor to limit the current under ~30A on the G2 motor driver. The battery is rated at 24V with peak current of 50A.

Hello.

The voltage on the current sense pin only changes by 20 mV/A, so it is not surprising that you are not seeing significant change from the standard offset of 50 mV. It is not the best tool for measuring low currents like 0.5 A, which would only correspond to a 10 mV change. Could you take a look at this with an oscilloscope and post screen captures so we can see exactly what the CS pin is doing?

-Patrick