IR Problems

James Penner

I have a Boe Bot (Basic Stamp 2 (BS2) Rev J and I am experiencing problems with IR sensors...So much so that I'm lost in isolating the problem.

Fundamentally, I set up the wiring for both Right and Left sensor pair, and perform simple evaluations with a White board about 1 foot away. One sensors pairs (left)·bounces around alot (eg 010100101001010). While the left sensor read correctly (eg 00000000000000).

I have:
- Varied the distance to the White board
- Used differnt materials for the wal
- Angled the sensors diferently
- Validated wiring & coding
- Replaced components (Transmitter & Receiver)
· - Right for Left/Left for Right
· - Old for New
- Created more complex (wiring and code)
· - Applying various resistances
· - Using AD5220 and experimenting with resistance variations.

Has anyone experienced a similiar issue with IR readings? What was the issue?

My next step is walk through everything again and document all my findings. Makes it easier to show the results of tests, and help eliminate issue....

Thanks for the help...

$WMc%

James Penner

You noted that You swapped IR units from left to right. Question ???, Did the out come swap from left to right ?

Walking through everything again and _documenting_ your findings will help others to help you, It will also help you keep track of the work you have done, And what it took to make it work!

If this was an easy hobby; We wouldn't be here!!!!

______________$WMc%__________________

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The Truth is out there············································ BoogerWoods, FL. USA

Sandgroper

Testing each side independently should pinpoint the source of the problem. I'd start by reducing the range to make sure that both emitter / receivers are well inside. You might be operating on the fringes.

You could try testing each circuit on the same set of pins. Make sure the other IR circuit - emitter and receiver - is totally disconnected when you try it. If the result is the same, repeat the test on the other pins. This should show you whether or not the problem is with the IR circuit. If it is, you'd expect one circuit to work on either side, and the other circuit to not work no matter which side it was on.

If both circuits are working correctly, you'd expect them to both work on one side but not the other. The next step would be to check the pins to see if they are going high or low, input or output, when they're supposed to. I'd start by checking the program (especially the tristate register). If the program appears to be OK, then check the pins with a pulse detector or multimeter to see if they're performing as they should.

Remember that the problem could be with the emitter circuit or the receiver circuit. You can check the emitters or receivers themselves by swapping them with the components from the "good" circuit. If they are OK, then test each input pin against either emitter pin. That should show up any problem with either.

Don't forget the effects of stray IR from other sources, e.g. overhead lights, other remotes, etc. I had heaps of problems with one circuit until I realised that the shadow from my hand was passing over the receiver! Inadequate or incorrectly positioned shielding can cause trouble too.