Jump to content

I bought a logic analyzer

Recommended Posts

So I bought this logic analyzer:



It seemed like a steal to me. I was just wondering if anyone has ever used one, or if anyone had any opinions about it. Wait, that was a lie. I think I'm just excited and wanted to brag. Still, what do you think?


If it saves me a couple long nights of tweaking and guesswork, I'll be happy. I think it'll make a good learning tool too.


I hope free day doesn't make it take a month to ship.

Link to post
Share on other sites

I've seen that one over on DangerousPrototypes.com quite a bit. It looks quite nice, and the (open source) software is under active development in many branches. I think it's worth it, but I wouldn't use it enough to justify buying one.


BTW: Did you get the $6 cable set(s)? The posts I've seen say they really add value to the device. You need two sets if you want all 32 channels. :D

Link to post
Share on other sites

I did buy that cable. I think I need 4 of them for 32 channels, so I went on dealextreme and bought some test clips. If I need more channels, I'll try making my own cable.


I don't know how justified I am in buying this, I just really wanted it. I might end up choosing projects just so I can use it.

Link to post
Share on other sites

I own one of those. Bought it when they released a first batch via http://seeedstudio.com. The same guys at dangerousprototypes also has Bus Pirate, which is also an awesome open source hardware. I have one and been quite satisfied with it.


Haven't played around with the openbench logic yet though. There's an interesting project called sigrok which should work with this logic analyzer. I've been following their development and it's still very much in progress.


But speaking of logic analyzers, I've been quite happy with this one: Saleae Logic.

Let me know what your experiences are with openbench. I'd love to hear about it.

Link to post
Share on other sites
  • 2 weeks later...

Well, I've been using it for a bit now. It's actually pretty useful in several applications I didn't expect. For example, I'm tinkering with an rfid reader. Its baud rate isn't easily divided down to from the default clock settings, so I decided to use something like a state machine to read the data. This involved setting up an interrupt to capture and handle the edge transitions of the serial data.


Well, it wasn't working. I had a suspicion that the interrupt was taking too long, and missing some transitions. In the past, I would have enabled Timer A and used it to count the cycles in the interrupt. Then I'd have to think about if the time would have an impact on operation.


With the logic sniffer, I just added 2 lines to toggle a pin at the beginning of the ISR, and toggled it back at the end. I hooked one lead of the sniffer to the toggled pin, and the other to the serial pin. From there, I was able to see how long the ISR was taking with respect to the serial data rate. I then moved the toggles around within the interrupt to determine which part was the biggest time-waster, and optimized that section. There was less guesswork, and I could get fast visual feedback on how my changes impacted the duration of the ISR.


I guess my point is, It's helped a couple times already, and I think it will help more and more as I figure out new ways to use it.


As far as how well it works... Well, it's pretty buggy, both on the hardware and software sides. It took me some reading and trial and error to figure out which settings play well together. Some settings when used together cause it to fail. Sometimes it just stops working randomly. The solution is just to disconnect it from the computer, reconnect it, and then restart the software.


At first, I was a pretty upset with the bugs. I was starting to think I'd have to make some contributions to the client software just to be able to use it reliably, but I didn't feel like putting another project on my plate. It turns out a lot of the issues are being worked on, and some of the workarounds I was using were documented. Now that I have a feel for what it does and does not like, it's pretty reliable. About 1 in 10 captures fail. Still, I only have to reconnect the device and restart software.


Overall, it's been useful to me, both for debugging and as a learning tool. If you want something that's completely reliable and user-friendly, it might not be a good choice for you, at least in its current state. However If you're like me, operating on a tight budget, willing to spend a little time learning to "play nice" with the system, and willing to deal with a few bugs, I think it's an excellent investment.

Link to post
Share on other sites
  • 3 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...