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Sony IR with m-Arlo BUG - SOLVED — Parallax Forums

Sony IR with m-Arlo BUG - SOLVED

WhitWhit Posts: 4,159
edited 2018-06-05 20:40 in Robotics
Since m-Arlo (mid-sized Arlo - see was completed on Memorial Day - I've been testing all sorts of code (modifying geometry for odometry) and making sure all is in good working order.

One consistent failure/problem/BUG from day one is that all the code I had for use with the Sony IR Remote - Failed in BlocklyProp, failed in C. All the code worked with the USB programming cable attached, but as soon as I disconnected it failed (when the power switch on the Activity Board WX was in position 2. I tried everything I could think of to solve this problem.

Got Parallax (Matt and Ken) involved yesterday - today the issue was solved. Andy Lindsay and David Carrier suggested as Matt wrote, "One new guess (Andy and David's suggestion) is to place a 0.1uF cap (the little yellow guy in many of our kits) across the power leads of the IR receiver. Miguel is going to try to duplicate the issue, but the reason for the cap is that motors are noisy, and the PWM driving them might be placing noise on the power lines - messing with the IR receiver." See photos attached.

GENIUS! - Everything works perfectly now! I don't know if I ever would have pieced this together (just would not have connected motor noise/PWM with the problem).

Sometimes in robotics - "It takes a village... especially if there are some really smart people living in the village." - (R) Trademark and copyright by Robotics Under the Stole ;-)

Thanks, TEAM Parallax!
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cap1.jpg 166.4K


  • ercoerco Posts: 19,904
    Interesting! Good to hear you got it sorted out. I've never had a problem with "those" IR receivers. There are dozens of different types, each with its own characteristics. I often see that people add a weak (high-value) pullup resistor on the signal line, but I've never needed that either.

    When in doubt, add filter caps everywhere. Especially important on a bigger bot like this, where significant current is gobbled up by the motors.
  • WhitWhit Posts: 4,159
    Thanks erco! I am much relieved!

    and thanks again to all at Parallax!
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