October 14, 2008 AT 1:46 pm

Quick tip: Analog signal from a ‘digital’ distance sensor

I accidentally purchased a GP2Y0D21YK0F when I meant to get a GP2Y0A21YK0F. The digital version only sends a high or low signal depending on whether there is an item within a preset distance. The analog version gives a 0-2.5V analog voltage depending on the distance (which is what I really wanted) Unfortunately, with a tight deadline & no time to reorder, I decided to see if the analog signal was still somewhere on the PCB, just not on the connector. A quick probe with my trusty scope says “yes”!


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6 Comments

  1. Good reverse engineering. The question of course is what are you building with it?

  2. I’m using the digital output units for a project and I appreciate this information. Thanks.
    what are your thoughts of the output of the digital sensor. My engineer has been pretty outspoken about this when trying to interface to our controller.

  3. With this method you get both an analog value to use and the threshold value that was already built into the distance sensor. w00t!

  4. Assuming your sensor is the same as mine, this mod can be done internally – you will need something to cut the trace though.
    http://img46.imageshack.us/my.php?image=d2asharp1xp7.jpg > your connector might be wired differently, but you get the idea :) Then you won’t see (or if space is an issue, have) a wire poking out the back. :]

  5. I like this, but answer me this…Why would this need to be done?

    I have an assortment of Parallax sensors, which are all digital, and the only thing I can think of is so you don’t have to use a timer with the pwm feedback to measure your input.

  6. Those Parallax modules aren’t digital in the true sense of the word, as they encode analog information into the length of the pulse, which has to be measured before a binary number is obtained. This sensor originally only gives an indication of the presence of an object within it’s range. A high reading means there is, a low reading means there isn’t.

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