User/Uses differences between logic analysers

[Galenbo]

I want a Logic Analyser, but don't know what I need.

I also don't know what I need it for.
I need it now for some playing around with 1-Wire, RS485, RFID, maybe Can,
but I don't know what the future brings.

I saw differences in the datasheets between these models:

-Open Workbench Logic Sniffer
-Bus Pirate V3/V4

But what do I need? What are the hidden possibilities/problems.
What about the user software? What can be measured/tested with these, what not/bad?

I already have the specs and comparison table, but please give me your User expieriences.

[Bored@Work]

Key to logic analyzers are the decoders. The open source ones you listed have rather bad ones, or no decoders at all. There is a good bunch of commercial USB based logic analyzers available with decoders, sometimes included, sometimes you have to pay extra. Get one of those.

What all these commercial logic analyzers have in common is they aren't build to last forever. They all use Windows, and at some point the driver and software will no longer work. So buy a commercial one that supports the protocols you need today and expect you have to throw it away in a few years. You anyhow have. Then buy a new one with the decoders you need then.

[Joshua]

I don't own one, nor have I ever used one, but my next purchase will probably be a Saleae Logic or Logic 16. It looks very nice and I like what I've seen of the software. All the reviews of it support it as well. Look at www.thesignalpath.com    He has done an in depth review of it and compares it against a competing analyzer.

[free_electron]

I get fristrated watching the signalpath videos because they are full of half truths and speculation. If you are going to do a teardown, make sure you know what you are talking about. Making statements as ' i guess its the same chip bacues it sits in the same package' makes you sound like an idiot.

Right. Om to the mistakes told in the teardown video.

First of all the salae boards both have overvoltage protection on the inputs. They use a series resistor in combination with a port protector. The sot23-6 devices have that on boards. These are similar to st's usb6b protections.
The center two pins are power and ground while the 4 corner pins each protect one input.
If you look at the video you will notice the 6 pin sto23-6 device left and right of the cpu on the 8 bit salea, and you will find four of them on the 16 bit version.

Second. The position of the fpga on the board has nothing to do with signal integrity or speed.
When they sample infast mode, the fpga actualy has a serializer on board. The shift data in at high speed and feed it parallel to the usb processor. Thatws why you only get a few channels.

[0xdeadbeef]

The Open Logic Sniffer is a logic analyzer and the bus pirate is more of a protocol sniffer, which also can be used as logic analyzer. Where "logic analyzer" means that you want to look at the timing of the signals while "protocol sniffer" means that you're only interested in the decoded data. Of course you can also use the timing data captured by a logic analyzer to decode the protocol (SPI/I2C/CAN whatever).
Generally, I would recommend the Logic Sniffer as a general debug tool over the bus pirate, which is more a specific hacking/sniffing tool.
Anyway, also the Zeroplus LAP-C16032 might be an alternative. It costs a bit more than a logic sniffer, but has better input protection, a case, a more capable software and more RAM, especially if you patch it to a C16128.
OLS and Zeroplus where discussed e.g. here
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/usb-logic-analyzer-%28sorry-long%29/
https://www.eevblog.com/forum/beginners/logic-analyzer-sample-rate-needed/

[typeglob]

I have the Saleae Logic 16 since a few weeks and quite like it. Unit feels well made and the software works pretty well. Exchanged some emails with the guys behind Salaea and they seemed quite responsive.

There are other logic analysers with much more protocol 'decoders', but at least the Salaea software has an SDK for writing your own decoders (I've written one for MIDI, wasn't actually that hard) and they have an API so you can use the hardware from your own software fairly easily.

I know they're looking for a professional developer to write some more 'decoders', so hopefully they'll have more in the not to distant future. In the mean time it might be nice if they would put up a section on their forum where people can post their own decoders.

From time to time I do find myself wishing I could change more in the software than just the decoders.

[free_electron]

I happen to know the guys from salae. They had an open house a couple of months ago and another a couple of days ago. I went there. Basically three hard working guys trying to make a quality product.
I got the impression they know what they are doing.