Roomba 530 encoders

I’ve been trying to read the signals coming off of a roomba’s wheel encoders and i cant seem to make it work no matter what i do.

The encoders use a hall effect sensor (i think) and there are 5 leads coming off the board (2 power and 3 for the encoder) The sensor has “90X” printed on it but i couldnt find specs for it. (pictures on this thread here

I’m going off the assumption that the wires are gnd vcc and signal. although i’m not sure which is which. and I’ve tried all 6 combinations (here’s to hoping that i didn’t fry it). but nothing seems to make anything happen.

Any suggestions?

Here is the sketch that I used

volatile int count = 0;

 void setup() { 
   Serial.begin (9600);
   attachInterrupt(0, interupt, RISING);

 void loop() { 

void interupt(){

I’m using an arduino uno r3.

I’ve attached the circuit of the encoder.

1)Is it possible to share Pinout Diagram for below model. 2)which arduino Board ur using?? 3)is your controller and encoder are on same ground potential 4)What is encoder output voltage level.

See Edits to original post.

Yes the encoder and arduino are on the same ground. and I have no idea what the output voltage level is. I couldn't find a data sheet for the IC.

The schematic for the encoder chip doesn't look right. The pin labeled "4" could be an output, but it is unusual to have a capacitor in series with a low value resistor between two pins.

The best way to figure out what the leads on encoder are doing would be to use an oscilloscope to examine all five, in an intact robot with the wheels spinning. If you don't have access to a scope, use a multimeter to measure voltages with respect to ground, on all lines, with and without the wheels spinning. On a meter the signal lines should show intermediate voltages when the wheel is spinning.

Five leads are found on some precision encoders with A and B quadrature plus Z (zero index), power and ground. However, Z would not be expected for a wheel encoder because there is no need for it.

If you have removed the encoder from the robot, keep in mind that the outputs might be open collector with a pullup resistor on some other board. In that case you would not see any voltage changes unless you add a resistor to V+.

Edit: This document shows how to interface (at least one type of) roomba wheel encoder: