B-328p Motor Driver + ACS711EX Current Sensor

I’m trying to monitor the current draw from the motor output of a b-328p. I’m using a ACS711EX Current Sensor.

I have plugged it into an arduino to watch the output of the Sensor. But I don’t get any change in the values from the sensor. they just stay the same where I have the motor turning or not.

here is a sample of some code that I’m trying.

Thanks a million for the help!

The print out just reads between 1023, and 990…

[code]int currentPin = A0;

float currentRaw;

void setup() {

void loop() {
currentRaw = analogRead(currentPin);


I am sorry you are having problems with your current sensor. From your readings, it looks like you are you measuring about 5V on that pin. I suspect something in your setup is incorrect. Could you tell me more about your setup? Which ACS711EX hall effect current sensor are you using, the ±15.5 A or ±31 A? How do you have the current sensor connected? Could you post pictures of your setup?

By the way, the ACS711EX is probably not appropriate for measuring the current draw from your Baby Orangutan. The motor driver on it is only capable of delivering 1 A continuously, which with either version of that sensor only corresponds to a change in the output voltage that is on the order of 100mV.

- Jeremy

Thanks for the help Jeremy! I’m using the ±15.5 A version.
I have it wired up the following way.

B-328p Pin M2B to ACS711EX IP+
ACS711EX IP- to Motor
ACS711EX GND to Arduino GND
ACS711EX Vcc to Arduino 5V
ACS711EX OUT to Arduino A0

If the sensor is isn’t appropriate, can you recommend one?

Thanks again for the help Jeremy!

Those connections seem correct. Could you post pictures of your setup, so I can see if there is anything obvious that could be causing a problem with the measurement.

The most sensitive current sensor we have is the ±5A ACS714 Hall effect current sensor. It outputs a proportional analog voltage of 185 mV/A and is intended for use in 5V systems.

  • Jeremy

Did anyone manage to figure out what was causing this problem? I have the exact same issue as dannyboy - the output voltage of the sensor is not changing at all which makes no sense. Thanks!


Why do you think you have the same issue? Could you tell us more about your setup? What is the sensor outputting? What is it measuring? How do you have things connected? Could you post pictures of your setup?

- Jeremy