QTR-8RC Reflectance Sensor Array Problems

Hi all,

I am using an Pololu QTR-8RC to follow a line, however am having some issues with it. I am running an Arduino Nano (using the Arduino Library).

Sensors 1 through to 6 seem to be working correctly, however 7 and 8 do not seem to be working.

When viewed with an older video camera (with night mode on), the sensor array looks like this,


(Sensors 7 and 8 are blinking). I have checked the power being supplied to the array and it is 5v.

My question is, what further testing can i do on the board? and is it usable? or time to get a new one…?

In the video the Nano is running the “PololuQTRRCExample.pde”


Hello, Julian.

I apologize that it has taken so long for someone to reply to this! Those sensors definitely should not be blinking like that. Have you soldered anything to your board other than the included headers, or have you made any other changes to the board? Did it ever work properly for you?

- Ben

Someone else was working on the project before me, so can no confirm that nothing other than the headers were soldered to the board, however by the looks of it - nothing else had been soldered. No other changes (that i know of) were made to the board.

I have since replaced the line sensor, but would still appreciate an explanation of what exactly was happening and why…


Sensors 7 and 8 can optionally be broken off the array to product a 6-sensor segment and a 2-sensor segment. Can you check to see if there is any sign that the connection has been broken? Is anything connected to the four holes on that side of the board? Could you post a clear picture of the strip?

- Ben