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Hooking up QRD1114 line sensor

Howto interface QRD1114 line sensor

Hi, everyone!

Few days ago one of our new members asked for help with QRD1114. I decided to answer in form of walkthrough, so others can benefit from it as well.

OK, should we start?! The QRD1114 line sensor (reflectance sensor) is easy to use. Personally, I can recommend it.

Where should we go first? Right, datasheet. We will need to dig some information out of it:

  • Pinout
  • Continious forward current of emitter = 50 mA
  • Forward voltage of emitter = 1.7 V (max)

Last two values are necessary for calculating resistor (see end of article).

The basic circuit for this sensor should look something like this:

Warning!!! Pins on schematic are not arranged as phisical ones! Refer to drawing and datasheet!

You will connect your power supply across V0 and V+. Out will go to ADC input of microcontroller. Depending on supply voltage and configuration of your emitters (if, say, you will use 3 line sensors, you might want to connect them in series or in parallel) you will need to recalculate/rearrange resistor which is in series with emitter IR LED. Here is nice walkthrough on how to do that.

Wasn't that easy? :D Good luck!

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Sorry to ring an old post, but this was very helpful. I've finally decided to get around to adding the encoders to the tracks for GRAB-E, which I always wanted to do. You post was clear and well written. I also found very useful info on Rudolf's post.

I've experimented with a few different surfaces for light/dark. Using paper with black marker pen, using black electrical tape, using the orange plastic of the Tamiya gears on GRAB-E, etc, with varying results. Placement of the QRD1114 seems key. I may try some of the variations on the resistor values that Rudolf tried. I may be getting too much reflected IR. Updates later on GRAB-E's build page.

Can you believe I refered to this my own post when I was building my LogoTurtleBot? :D

Completely. Why remember when you can post and lookup later! ; j

If the pin arrangement isn't all that favourable you can pop the LED and phototransistor out of the plastic housing and shift/rotate them around. Of course, you should probably take note of which coloured lens each component has, and which lead is which before removing them =)

Fortunately positive lead of each part is longer than negative, so, unless they have been cut, one only need to distinguish between emitter (transparent lens) and sensor (darkened lens). Thanks for tip, Tele! :D

This absolutely great. Thank you for posting, Isotope! :)

The warning you give is quite important .... a while back i killed my first QRD by not checking the actual-against-schematic ......

I did lots of errors with my first QDR's, soldered/unsoldered them loads of times, wrong polarity, every possible mistake, i was so surprised when i hooked it up properly and it worked :O

i soldered mine ok for first time but second time i hooked up the emiter in place of the reciever and vice verse :D