Tuesday, October 18, 2011

Scopes and electronics

An oscilloscope is very important for any electronic enthusiast. Recently I have been trying to send IR remote codes from an arduino board to my TV. I was having some trouble with timings and my TV would not respond properly. Without the oscilloscope this would not have been easy to debug.

I have been looking for some not very expensive, simple to use oscilloscope that can be connected to my computer, so I can save data. I came upon PicoScope. They have a wide variety of products, but the one that caught my eye is the PicoScope 2205 which came in my budget and good enough for my projects. However it is not available in India. Lucky for me my sister and brother-in-law are in UK! I asked them for the PicoScope 2205 and 2 probes (x1 and x10). Thanks to them I now have an oscilloscope.

Contents of PicoScope 2205 and Probes

So when I had to find the IR signal coming from my TV remote, I connected the probe to the IR receiver data out pin on the arduino board and started recording the signal using the PicoLog software. It is really simple to use PicoLog. I did not even read any manual or help files. Launched the app, started a new recording and setup the recording method to "Fast block", and "Stop" action at the end of one run.

Then the recording parameters have to be set a bit. Basically I went for 5 us time base (the lowest I could go to get a full command from my remote) and maximum samples possible. That makes for a 81 ms recording time on the PicoScope 2205 buffer. Good enough, because I know that the signal cannot last for more than 45 ms. I set the range on Channel A to 5V DC.

Finally I had to set the trigger on Channel A to "Falling" direction. That is because I found that for some reason the data out pin on the IR receiver is high when there is no signal and goes low when it detects a IR signal. Set the threshold to 2000 mV, but higher would also work. Just wanted to be on the safe side.

That's it for the configuration part. Next I connected the probe on the data pin of IR receiver and pressed the volume up button on my remote. The trigger happened, data got recorded by PicoLog and this is what I got.

I see a lot of other uses for my oscilloscope in future. I suggest you get one too if you are serious about electronic projects.
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