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Topic: Loginc Analyzer advice please (Read 1 time) previous topic - next topic

Graynomad

#5
Mar 28, 2013, 03:11 pm Last Edit: Mar 28, 2013, 03:15 pm by Graynomad Reason: 1
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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Rob

Rob Gray aka the GRAYnomad www.robgray.com

Retroplayer

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.

dicky96

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

Graynomad

Quote
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.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

dicky96

Thanks again for the recommedations:

I do like the look of this 

OK so it is not 40MHz but it looks...... colourful lol ]:)

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  :P

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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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