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Infrared Issues With BOE Shield Bot — Parallax Forums

Infrared Issues With BOE Shield Bot

regretregret Posts: 5
in Robotics
My robotics class is currently working with the BOE Shield Bot on Chapter 7: Navigation With Infrared Headlights. However, we have run into an issue: The first activity, TestLeftIR, always returns a 0, whether or not anything is in front of the bot. This is not exclusive to my partner and I, as the teacher has the same issue with his bot. The right side works with no problems.

We have tried everything. We have switched all the components from the working right side to the left, tried activating the reciever with a remote, retyped the code, and checked our circuit over and over.

The only thing we have found is that the output pin on the IR Reciever itself, when measured with a multimeter, is only outputting around 1 volt. We have a 5V board. The working reciever on the left side outputs around the same 4 volts as it gets, so we aren't quite sure why this is. The only way to fix this is to remove all of the other wires connected to the reciever besides the jumper cable supplying the power, but its sort of useless, since connecting it back to it's pin just brings the voltage way down again.

As you can imagine, class has been pretty frustrating the past few days. My partner and I would be really glad if anyone could help us. Thanks!

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2016-11-02 22:59
    Swapping the IR Detectors is a step in troubleshooting, however you didn't mention whether or not the issue follows the detector. Most of the time we find these are simple wiring issues that get missed, but a photo of your connections would help ensure everything was correct.
  • ercoerco Posts: 20,254
    Sounds like a bad IR receiver. Is this setup still the IR receiver in the breadboard next to an IR LED? If so, first remove the IR LED and measure the receiver output voltage. Make sure there is no other device nearby emitting an IR signal. Output voltage needs to be over 3.5V or it's a bad receiver. These are commonly available 38 khz types, you can replace with most any you find. A few bucks each.
  • regretregret Posts: 5
    edited 2016-11-03 15:03
    I forgot to mention that it does not follow the reciever, sorry. Here is a picture of the connections. Thanks!
    Chris Savage wrote: »
    Swapping the IR Detectors is a step in troubleshooting, however you didn't mention whether or not the issue follows the detector. Most of the time we find these are simple wiring issues that get missed, but a photo of your connections would help ensure everything was correct.



    IMG_1166.JPG
    4032 x 3024 - 2M
  • regretregret Posts: 5
    Thanks for the suggestion! However, we have tried swapping the nonworking side's IR reciever with the working side's IR reciever, and there was no change in our results; the right side still worked fine, and the left still kept displaying a 0. Also, our robotics teacher is having the exact same issue with his bot and parts, so it's unlikely that we all have bad recievers that just happened to end up on the left side.
    erco wrote: »
    Sounds like a bad IR receiver. Is this setup still the IR receiver in the breadboard next to an IR LED? If so, first remove the IR LED and measure the receiver output voltage. Make sure there is no other device nearby emitting an IR signal. Output voltage needs to be over 3.5V or it's a bad receiver. These are commonly available 38 khz types, you can replace with most any you find. A few bucks each.

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    Your wiring doesn't seem to match our diagrams here: http://learn.parallax.com/tutorials/robot/activitybot/activitybot/navigate-infrared-flashlights/build-ir-sensor-circuits

    It also looks like you're using the wrong resistor value on the IR LED.
  • regretregret Posts: 5
    The resistor values match the diagram we are using from here:
    http://learn.parallax.com/tutorials/robot/shield-bot/robotics-board-education-shield-arduino/chapter-7-navigating-infrared-10
    Chris Savage wrote: »
    Your wiring doesn't seem to match our diagrams here: http://learn.parallax.com/tutorials/robot/activitybot/activitybot/navigate-infrared-flashlights/build-ir-sensor-circuits

    It also looks like you're using the wrong resistor value on the IR LED.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2016-11-03 16:01
    I see...this is what happens when you get a call for an ActivityBot while responding to a thread about the Shield Bot. Okay, so your wiring looks okay except your servos. They're not in the correct ports. And the ports they are in would seem to interfere with the IR LEDs since they use one of the same I/O pins.'

    Note that your servos are connected to P10/P11 while the IR Detector (left) is wired to the same pin. Please move the servos over to P12/P13 and try again.
  • regretregret Posts: 5
    Thank you so much! Our robotics teacher had us hook them up to P10 and P11 for some reason, and I didn't think it could interfere with anything. We'll try the different pins tomorrow.
    Chris Savage wrote: »
    I see...this is what happens when you get a call for an ActivityBot while responding to a thread about the Shield Bot. Okay, so your wiring looks okay except your servos. They're not in the correct ports. And the ports they are in would seem to interfere with the IR LEDs since they use one of the same I/O pins.'

    Note that your servos are connected to P10/P11 while the IR Detector (left) is wired to the same pin. Please move the servos over to P12/P13 and try again.

  • ercoerco Posts: 20,254
    @regret: NOW we're getting somewhere. If everyone posted such clear and detailed photos as you did, issues would get sorted out very quickly.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    erco wrote: »
    @regret: NOW we're getting somewhere. If everyone posted such clear and detailed photos as you did, issues would get sorted out very quickly.

    #TRUTH

    A picture often is worth a thousand words.

  • PublisonPublison Posts: 12,366
    edited 2016-11-03 17:34
    I would also move the Right, (bottom in the picture) IR Detector to the left, (up), as to not block the IR emitter.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    Publison wrote: »
    I would also move the Right, (bottom in the picture) IR Detector to the left, (up), as to not block the IR emitter.

    Both emitters really just need to be pointed more downward so they're below the IR detector. That would work without having to relocate them.
    :thumb:
  • PublisonPublison Posts: 12,366
    Chris Savage wrote: »
    Publison wrote: »
    I would also move the Right, (bottom in the picture) IR Detector to the left, (up), as to not block the IR emitter.

    Both emitters really just need to be pointed more downward so they're below the IR detector. That would work without having to relocate them.
    :thumb:
    I just though it would be better to position the Emitters a Detectors the same on both sides to alleviate any blockage. And it looks better. :)
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