Protocol analyzer: advise/recommendation needed

Hi Everyone,

I'm looking for a protocol analyzer, more precisely to analyse I2C and SPI

the "perfect" analyzer would allow me to:

  • Start the analyzer
  • capture all packets going on the wire
  • stop when full or manually stopped
  • display the result such as source, destination, command, payload, for each captured packet

I have a budget of 150-250$

any recommendations ? any device to avoid ? better software than other ?

Saleae Logic 8

I don't think I2C, SPI are typically thought of as having packets. I suppose they could if the protocol you write uses them that way, or maybe for multibyte transfers.

Most logic analyzers will do that. Even the cheap (<$10) USB units from China that work with Saleae Logic V1.1.15. They can take up to 10 Billion samples at up to 24 MHz on 8 channels.

I used the word "packet" but it's actually the string being pushed on the wire itself that I'm referring to.

johnwasser: any software that is going to be more "user friendly" than another ?

I borrowed one from a colleague, and the software was a pure piece of

You borrowed what?

I borrowed one of those mid-price analyzer (50$ he paid)

Once acquisition was done, it had no real protocol analyzer.

The capture was a stream of bits, and zooming in was extremely painful...

50$ wasted IMHO...

That's why I am willing to pay a bit more, but end up with something usefull !

You can try the software. It has a simulation mode to use if the hardware is not connected:
https://www.saleae.com/downloads

Of course the latest software is not supported by the clones of earlier hardware. You would have to get the genuine "Logic 8" for $219, well within your price range.

Johnwasser: do you know if it is worth buying the genuine thing or if the clones (using an earlier version) shall be just fine ?

anyone ever played with either version to analyze I2C ?

I have one of the new Logic 8's. I've only pulled it out a few times, but it was very helpful debugging some glitchy SPI comms on a project. I should think it will do just as well with I2C, Serial, and so on. The software is excellent. Personally buying a clone never even entered my mind, Saleae put a ton of time and effort into developing the software and hardware, buying the genuine article is part of paying them back for that and helping keep them around. That, and I don't trust cheap Chinese clones of pretty much anything to actually stay working reliably.

There are a few other devices out there for a little less that look to work OK, but the software was what drew me to the Logic. Test drive it, see if you like it, then buy one if so.

As a hobbyist I can't justify spending over $200 for tool I don't really need. I bought the Chinese clone for $15 and am happy with it. Like the older Saleae model it only does digital and only 24 MHz (the Logic 8 does digital at 100 MHz and all 8 pins can also do analog at a lower rate).

clones
Or
ripoff?

The older 8 channel is the model I have, was only $150 a couple of years ago.
Didn't realize they had improved its capabilities so much.
Did come in very handy for finding the optimum way to run SPI at 8 MHz and show that the
millis()/micros() interrupt was disrupting my high speed data bursts.

just ordered one of those Chinese Saleae compatible....worst case, my loss is going to be below 15$

Will let know know how it worked !

Hi Everyone,

I just received my Chinese protocol analyzer. In the meantime, I bought another one on Ebay. It's a ZeroPlus, LAP-C16032.

As promised, here are my impressions:

Chinese one: paid 14$ on Ebay. Easy to use; it requires you to download the software from Saleae (www.saleae.com).

The software couldn't be simpler. it has very few settings that you can change. You can specify a trigger, and is is very rudimentary. I tried it to capture activity between 2 uCPU over I2C.

You can capture A LOT. it saves it either on RAM or HD (don't know/don't care ). the I2C analyzer will tell you who the message is addressed to, if it's a read or write and the data. these info are shown along the continuous string of captured data.

Scrolling thru the packets is a bit painful, but it can be done ! The number of available protocol, is somehow limited, but it has the one I was looking for (I2C, SPI, DMX512 & 1-wire)

Consider buying some "clamp-on" cable. (a 'big' 8$ investment)

ZeroPlus (www.zeroplus.com.tw):

140$ on Ebay. Holy ...we are not talking about the same thing !!!

Tons of settings/tweeking. Again, you can specify a trigger to start acquisition.

The captured trace are shown on a continuous string of captured data, showing the same info as the Saleae did. But, you can decide to display the captured packet on visual list . This is simply great !!!! Clear & efficient.

The downside, is the memory size: mine has 32K, so I was able to capture only 8-9 packets. quite deceiving, until I discovered that you can use some kind of lossless compression. same system, I was then able to capture 630-ishh packet.

there are 50+ protocols supported. Most of the ones I wanted were provided for free. Then, you can select up to 30 more protocol. I then choose Modbus, ProfiBus, HART, and a couple more. Still got a 'bank' of over 20 protocols to pick !

The unit has a total of 512K. It would have been nice if I could have used that 512K over 'x' number of channel that I would have enabled....but, as per tech support, it's not the case.

There are a few hacksite that explain how to transform it from a 16 channel to a 32 channel, and how to increase the memory. Not there yet !

Conclusion: if you are on a budget, the chinese stuff might be OK. If you can spend a bit more, go for the ZeroPlus, no hesitation. If you can afford it, maybe go for the 64K or even 128K. You get what you paid for !

I'm also looking at another company called CWAV. They make the USBee SX, which seems to have a software as user friendly/powerful as the ZeroPlus, with the option to store captured data on HD. The specs themselves are similar to the ZeroPlus. Price is 170$. I might end-up having 1 or 2 logic analyzer for sale at the end !!!

Now for those hyper-technical guru here, yes, there are probably better logic analyzer, my review is probably incomplete, I could have done better testing, etc ... I know all that. This is just my personal opinion, of something that does what I was looking for !!!