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Author Topic: Loginc Analyzer advice please  (Read 1262 times)
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Sorry don't know which section to put this in or if it is really apprropriate...

I have played around with a bus pirate logic analyser and found it very useful to help debug i2c transactions

However it has a lot of limitations (esp small buffer size and inability to trigger on specific data bytes using OLS)

I' in the market for a better analyser but there are so many options

Can anyone recommend the best analysers say in the £200 ($300) and the £500 ($750) price brackets - or less if there is something really good worth a look

I ideally want something fast with a lot of memory - something that would enable me to capture i2c and SPI traffic (up to 400MHz bus) over long periods of time - somtimes this is because of intermittent communication with 5 mins gap between traffic.... or more) would be ideal

I've tried asking this on boards specific to one product or another but they don't seem to want to talk about other alternative devices so I thought I would ask somewhere more generic - like here

There seem to be a lot of anaysers on the market (sparkfun USB, saleae, logic sniffer) but just looking at sales sites does not give a lot of info what is good and what is not

Rich
« Last Edit: March 27, 2013, 07:20:27 pm by dicky96 » Logged

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Well, I would rule out the LogicPort. This is the only one that I currently own and it has horrible sample depth and I am not a fan of the triggering. But it was the best out there back when I bought it.

You might be asking for a bit much in that price range. There are several that meet one or two requirements you listed, but I don't know of one within that price range that meets all of them.

These are more than twice your listed price range, but you might want to take a look at http://www.linkinstruments.com
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up to 400MHz bus) over long periods of time
up to 400MHz, yes, over long periods of time, yes, both, no. At least AFAIK in any reasonable price range.

Are you serious about the 400MHz? That's not I2C or SPI.
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Rob Gray aka the GRAYnomad www.robgray.com

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Sorry I put an extra 0 on the MHz!!  smiley-eek

Something fast with good sample depth, a protocol analyzer and the ability to trigger on certain data sequence, or to capture events on serial bu, then 'go to sleep' until the next event then capture that.... would be ideal
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So up to 40MHz? Well, the LogicPort would support what you are suggesting for the most part. You can have it trigger continuously and also set it to export on acquisition. I still wouldn't recommend it as it has such a shallow sample depth. Even the Open Worksbench Logic Sniffer has more sample depth and is hundreds of dollars cheaper.

The features that you want are more dependent on software, though. That is also a place where the LogicPort does not shine well. And it is completely closed without even an option to purchase an SDK. Another reason I have been seriously considering getting the Logic Sniffer since it uses the open-source SUMP software. I don't have it yet so I cannot give any sort of review, unfortunately.  But at $100 for the mainboard, 16 bit expansion wing, and all the probes, you really can't go wrong to try it and see. The only reason I haven't so far is because I am saving my pennies for a 3D printer right now.
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A lot of people (myself included) use the Saleae LAs, they are great but won't go to 40MHz unfortunately.

USBee have some nice-looking units

http://www.usbee.com/products.htm

But it seems the only one that does 40MHz costs nearly $2k.

I've always liked the look of LogicPort but there's the sample depth and what Retroplayer says about it.

I'm out of ideas at this point, unless you can drop the sample rate, in which case you can't do better than a Saleae Logic.

EDIT: Stop the press, I forgot about the Saleae Logic16, that will do 100Mhz @ two channels, 50MHz @ 4 channels etc.

http://www.saleae.com/logic16?gclid=CJrolrnLn7YCFUYhpQodZEkAbA

Ask Nick Gammon about it, IIRC he has one.

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« Last Edit: March 28, 2013, 09:15:15 am by Graynomad » Logged

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My main gripe with the Saleae stuff is the lack of an external clock input. So you need to get creative with your triggers. I do have the 8 channel version, but I have not used it a whole lot. There may be all kinds of ways around that that I am not aware of.

One advantage is the buffer depth is only limited by the size of RAM in your computer. However the actual sampling rate is limited to the speed of the USB bus since the transfers are in real-time.

Coming from using a standalone logic analyzer, I never really wrapped my head around the Saleae LA. Maybe I should dig it out again. I love how small it is and the majority of the time, I am looking at stuff with fewer than 8 channels anyway. The LogicPort is actually kind of clumsy to hook up for such few signals.

And, Gray, yeah... the look of it (and the 34 channels) is what had sold me on it. As I said, the market was pretty limited for these at the time and it was the best at a reasonable cost. Lots of better ones out there now. I can't believe they are still able to charge as much for it with the better competition now.

I have also been looking at the ZeroPlus models and their clones. A big factor for me, personally, is support in sigrok or SUMP since I find the software is where I usually get disappointed.
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I've been recommended the Logic Sniffer (but probably because I asked at the Bus Pirate forum) but I hear that does not have a large sample depth?

The 40Mhz is just a wish list thing

What I would like is an anaylser that can cope with SPI at any speed i am likely to come across, and has a large sample depth so I can cope with intermittent data packets in i2c and SPI.  I had another go with my Bus Pirate on SPI, toggling a spare pin on the Arduino to use as a trigger on the spare channel 5 of the Bus Pirate, and had more success than before

BTW is the clock supposed to be varying widths when the Arduino acts as a SPI Master?  I expected a steady clock like I see on i2c

I will have a look again at the Saleae Logic 16, I did spot this one before

Any other suggestions welcome

Rich
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is the clock supposed to be varying widths when the Arduino acts as a SPI Master?
I would not expect so because it's hardware driven and should be stable, there may be a gap between bytes though.

OTOH there's no reason not to vary the clock with SPI.

What are the sample and target clock speeds? If you aren't sampling fast enough relative to the sampled data you will get an effect that looks like the clock varies. This is were the external clock that Retroplayer mentioned can be handy.

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Thanks again for the recommedations:

I do like the look of this 

OK so it is not 40MHz but it looks...... colourful lol smiley-evil

And it is within my price range £375 + VAT = £425

And it's a shame you have to pay extra $299 if you want the pro version of the application software  smiley-razz

-------------

And I also like this which is a lot cheaper, fastet? more channels (plus I can get one in the UK within a couple days)

http://www.saleae.com/logic16
http://www.saleae.com/logic16/specs

£249 inc VAT and postage


Anyone have experience with these two help me make the best decision

Rich
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Anyone have experience with these
Try Nick Gammon

http://arduino.cc/forum/index.php?action=profile;u=36095

He's a moderator here and I'm sure he has the 16-ch Saleae

I have the 8-ch version and I can vouch for their support, it's really good.
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is the clock supposed to be varying widths when the Arduino acts as a SPI Master?
I would not expect so because it's hardware driven and should be stable, there may be a gap between bytes though.

OTOH there's no reason not to vary the clock with SPI.

What are the sample and target clock speeds? If you aren't sampling fast enough relative to the sampled data you will get an effect that looks like the clock varies. This is were the external clock that Retroplayer mentioned can be handy.

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Rob

I'm sampling tried a few sampling rates  

At 4Mz (the max available)and setting SPI_CLOCK_DIV16, the clock looks all over the place, and yes I am reading garbage data that changes every time I reset the Arduino and re-capture the same even- I suspect my Bus Pirate ain't fast enough for this sort of job  smiley-roll
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OK had a another play around

At SPI_CLOCK_DIV128 and 4Mhz samplin on the Bus Pirate I can get consistent results  smiley

But I still want a better analyser  smiley-twist
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Not had a reply from Nick yet but I seem to have convinced myself already

logic 16
Version 1.1.9

    Increased Logic16 USB bandwidth performance by 50%! Old limits were 2 ch @ 100MHz, 4 ch @ 50MHz, 8 ch at 25MHz, and 16 ch at 12.5Mhz. New limits are 3 ch @ 100MHz, 6 ch @ 50MHz, 9 ch @ 32MHz, and 16 ch @ 16MHz.

this seems unbeatable value for money IMHO looks like I wll have a nw toy next week  smiley-twist
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Ooops sorry my apologies I did have a reply from Nick

His opinions settles it for me - deffo have a new toy coming......
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