Logic Analyser

[Hippogriff]

Hi all,

My next challenge - on my long learning-electronics path - is to understand a bit about IR remote control. You all know that my projects are about PICs (with JAL) controlling RGB LED strips via PWM and I've moved on to switches and potentiometers as I've progressed.

Now I've bought myself an IR remote control designed for lights - one with the buttons on for different colours and Fade and Strobe etc. - and I want to see if I can figure out how I might control my RGB LED strips with a remote.

So far, I have the IR remote, some TSOP IR Receivers... and my PICs. I have TSOPs running at 36KHz and 38KHz (just in case - as I don't know much about the remote itself).

I figure I connect the TSOP on a breadboard, point a remote at it, and then I'd need to decipher the pulses the TSOP outputs to a PIC input pin, in my JAL program. The theory is fine. How I get to that point is the tough part. I have no idea what the TSOP is spitting out and no way to analyse that.

So, I figured that I now need a logic analyser - to see what the TSOP emits when an IR remote button is pressed. That's the nub of my question... I don't yet have a PICKit II (which has a logic analyser feature) as I use a different (bought, not built) programmer but I've also seen the Saleae Logic () and it looks pretty good.

I wondered if anyone had any advice on the two options in front of me - or others? I don't want to go building something (I think it'll be beyond me for the time being) so I am looking for something off the shelf. The PICKit II is cheaper, but I often work on the "one tool for one job" mantra, so would the Saleae Logic be a good investment to not only get me past my current challenge, but also be invaluable in the future? It's about €149 plus shipping, so it's more expensive, but not Earth-shattering in £s.

One thing that concerns me about the Logic is the statement on their Tech. Specs. page which says "Logic may not be used with DUTs (devices under test) which are not electrically isolated from MAINS (i.e. wall power)." - I always use my bench PSU for project testing... I'd not want to ever risk frying my laptop via the USB port.

As always, advice and guidance appreciated.

 

[3v0]

I have the Saleae and like it. The I2C and SPI post processor are very handy

As far as I know SMPS are not isolated but considered safe by most people. I would ask for clarification of the isolation bit as not using with SMPS would be a big problem.

 

[BrownOut]

Have you seen this? https://www.electro-tech-online.com/threads/low-cost-logic-analyzer-small-in-size-big-in-features.113985/

Bench PSU's are almost always isolated.

 

[blueroomelectronics]

My little Junebug kit can see TSOP1138 signals just fine, it even includes one on the tutor.
https://www.electro-tech-online.com/threads/junebug-ir-remote-protocol-viewer.38313/
**broken link removed**

 

[BeeBop]

Statements like this:

Bench PSU's are almost always isolated.

get guys like me in trouble!

I've gotten into the habit of always checking.

I recently repaired a spot welder, where an Electrician had mixed up two wires of three. He had the PE (ground) connected to Line, and Line to PE! Good thing the case was powder coated.

Also have seen more than one isolation transformer, where the PE's were connected.

If I forget to check, the sparks are a lively reminder!

 

[BrownOut]

You can usually look through the cooling louvers and see the transformer in the PSU. Also, if it's heavy, it usually has a line transformer. But sure, always check.

Just a thought, you could always connect a lamp to the "+" lead, and then to the ground ( or return ) connection of the wall receptical. If the lamp glows, then you don't have an isolated supply. Adjust the supply output to the voltage of the lamp.

 

[3v0]

You can usually look through the cooling louvers and see the transformer in the PSU. Also, if it's heavy, it usually has a line transformer. But sure, always check.

Just a thought, you could always connect a lamp to the "+" lead, and then to the ground lead of the wall receptical. If the lamp glows, then you don't have an isolated supply. Adjust the supply output to the voltage of the lamp.

I tested the EXTech 382200 and the little 200 ATX PSU I just drafted for fixed voltages. Neither show voltage between positive terminals and the case which is connected to the line cord ground (Know the AXT PSU is assume the EXTech is too). Ohm meter also shows no connection from ground terminals and the case.

That makes me feel a bit better.

 

[Hippogriff]

Thanks guys...

I'm going to ask the girlfriend if she'll get me a Logic for my birthday. See how that goes down... probably like a lead balloon, but we shall see.

 

[OlPhart]

IR remo method...

Built my 1st in '98 in C+ for DOS, in '05 did a VB/Windows version that has a hardware block doing the I/O & required timings on a 908JL16 through USB.

So, I use a set of timing parameters: start on the 1st active edge & count to the next transition. Log the count, reset the counter & repeat until an idle state is seen. I use the overflow of the counting tank. The trick is to use a big enough counter to not overflow on a valid signal span, And to make the input counting software have the same execution time as the output. You can use a square wave as input & verify the same frequency on output to check/tune.

Simple hardware is an IR receiver for input & a 555 at carrier frequency to an IR LED as output.

Good Hunting with this, it's a fun project with a useful result. Mine runs the A/V system like a big universal remo, but Really programmable. <<<)))

 

[Hippogriff]

Just an update... I purchased a Saleae Logic and I have used it to good effect in solving the problem I had. In fact, it made it all quite easy to be honest. I could never have done it without it, of course. Impossible task. So, although I don't yet know what else I might use this for, I think it's a really good purchase. It's a very nicely put together package - both hardware and software - simple enough to get immediate results and has other features I've not had the need to look into yet. The guys who create and sell this thing are also really friendly and have kept up good communication and also seem willing to take on a few ideas I had about their user manual and Logic software. Overall? I'm really chuffed and I can detect the pulses coming from the remote control I have with my PIC and distinguish between them all... all I wanted.