Author Topic: USB Logic Analyzers  (Read 14212 times)

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Offline smbaker

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USB Logic Analyzers
« on: October 16, 2017, 03:50:13 am »
I'd like to get a logic analyzer for use with some retrocomputing projects that use a bus speed of 4 - 16 Mhz. Checking ebay, I can find the following:

* Salae 8-channel 24 Mhz for around $6
* Salae 16-channel 100 MHz for around $43
* SeeedStudio 16-channel 100 MHz / 4-channel 400 Mhz for around $75

I'm thinking the 16-channel 100 Mhz products fit my use case with room to expand. The 8-channel 24 Mhz is appealing solely because at $6 if I do something stupid and ruin it, I can throw it away and not feel bad.

Any experiences with these products? is the software decent?

Scott
 

Online ataradov

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Re: USB Logic Analyzers
« Reply #1 on: October 16, 2017, 04:02:13 am »
$6 Salae are clones, otherwise they work perfectly, if you don't feel guilty about this kind of stuff.
Alex
 
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Offline blueskull

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Re: USB Logic Analyzers
« Reply #2 on: October 16, 2017, 04:48:38 am »
Guilty? Guilty for what? Nobody forces you to use Saleae software. Sigrok is there for you, free of charge, open source.
 
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Offline trevwhite

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Re: USB Logic Analyzers
« Reply #3 on: October 16, 2017, 07:43:26 am »
You can get the usbee clones as well and pay for the software license

Sent from my SM-G950F using Tapatalk

 

Offline Gabri74

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Re: USB Logic Analyzers
« Reply #4 on: October 16, 2017, 08:41:35 am »
I second buying a cheap Chinese logic analyzer as your first analyzer and using sigrok, perfectly legal and moral :-)

I think that also buying an DSLogic clone and using their original software is somewhat moral because basically the cloned sigrok PulseView, refined some future and refused to release source codes (which the where obliged to bye the GPL) for a long time.

See this great video for a primer on sigrok and a comparison of various cheap ebay logic analyzers (done by the main PulseView developer):

 
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Offline MrW0lf

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Re: USB Logic Analyzers
« Reply #5 on: October 16, 2017, 08:54:44 am »
Are you taking into account that 24MHz one sampling rate will drop to nothing when all 8 enabled may struggle on full rate (see OTL video)? 16-ch version will drop also of course but to less appalling levels.
Due to TEO syndrome I have 6 devices that could be used for this kind of activity and was thinking to do review maybe but struggle to find motivation because most comments will be probably "just buy $6 one" :D
« Last Edit: October 16, 2017, 09:55:53 am by MrW0lf »
 
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Offline abraxa

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Re: USB Logic Analyzers
« Reply #6 on: October 16, 2017, 09:36:09 am »
Quote
I'd like to get a logic analyzer for use with some retrocomputing projects that use a bus speed of 4 - 16 Mhz.

I suggest you get a 8ch one for $6 and use PulseView with it. That way, you can figure out what you like/don't like and what exactly you need, should you need something bigger.

Quote
Are you taking into account that 24MHz one sampling rate will drop to nothing when all 8 enabled?

How so? The Cypress FX2 always transmits 8 bits per sample (except for when it's told to send 16 bit), so enabling/disabling individual lines doesn't change anything. The main thing affecting the sample rate is the USB connection - a cheap/bad USB cable makes the connection unreliable, resulting in unsuccessful data acquisition.
 
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Offline MrW0lf

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Re: USB Logic Analyzers
« Reply #7 on: October 16, 2017, 09:54:29 am »
How so? The Cypress FX2 always transmits 8 bits per sample (except for when it's told to send 16 bit), so enabling/disabling individual lines doesn't change anything.

Ok, thats the one I do not have - seem have to buy all of them to stay informed :palm: Thought it is similar to others in that regard. I just bought 100MHz one after watching OTL video which showed that $6 one wont manage 24MHz reliably. Overall I find massive oversampling useful because it works sort of scope then and will give timing info.
« Last Edit: October 16, 2017, 09:56:39 am by MrW0lf »
 

Online TK

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Re: USB Logic Analyzers
« Reply #8 on: October 16, 2017, 10:50:28 am »
For retrocomputing projects you are better with 32 channels: 16 for address bus, 8 for data bus and 8 for control signals.  8 channel logic analyzers are useful for serial decoding.

I know modern USB logic analyzers are more practical.  I have one but I also got an old HP 1670D that can do timing and state analysis and with the right information, you can also do microprocessor (Z80, 6502, 6800, 68000...) inverse assembly.  It does not take much bench space like the 16500 or 16702B.  The 1670G is more modern with color LCD screen, but a little more expensive.  You can get 1670D in decent shape with all the cables and some probes for around $150 on eBay.
 

Offline MrW0lf

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Re: USB Logic Analyzers
« Reply #9 on: October 16, 2017, 10:58:25 am »
For retrocomputing projects you are better with 32 channels:

Aha, have one for that:
http://store.digilentinc.com/digital-discovery-portable-logic-analyzer-and-digital-pattern-generator/
Quote
32-channel digital logic analyzer (1.2…3.3V CMOS, 8 channels at 800MS/s*, 16 channels at 400MS/s*, and 32 channels at 200MS/s)
...
*Note: to obtain speeds of 200MS/s and higher, the High Speed Adapter must be used.
...
Setting the voltage to 3.3V, 5V logic inputs are tolerated but the input threshold is 1.42V. LVCMOS 3.3V output signals are compatible to most external logical circuits supplied with 5V.

But no doubt proper boat anchor would squash it :P
 
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Offline technogeeky

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Re: USB Logic Analyzers
« Reply #10 on: October 16, 2017, 12:51:03 pm »
I second buying a cheap Chinese logic analyzer as your first analyzer and using sigrok, perfectly legal and moral :-)

I think that also buying an DSLogic clone and using their original software is somewhat moral because basically the cloned sigrok PulseView, refined some future and refused to release source codes (which the where obliged to bye the GPL) for a long time.

See this great video for a primer on sigrok and a comparison of various cheap ebay logic analyzers (done by the main PulseView developer):



That guy makes some excellent videos. Really incredibly well put together videos.
 

Offline smbaker

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Re: USB Logic Analyzers
« Reply #11 on: October 16, 2017, 04:44:23 pm »
After watching the video, I'm considering the DSLogic, as it seems to offer some advantages over the saleae clones. Buffering seems useful, I like the idea of being able to get ~ 100 Mhz bandwidth at full channels. Even if I'm operating at a maximum of 16 Mhz bus speed on my projects, the oversampling would allow me a better shot at detecting timing issues.
 

Offline 0xdeadbeef

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Re: USB Logic Analyzers
« Reply #12 on: October 16, 2017, 05:20:21 pm »
I have a DSLogic (Pro), well actually I have two of them and the hardware is great, but keep two things in mind:
1) There are different versions sold on eBay where some use a weird high density probe connector which means that you can't connect normal jumper wires to the device and are screwed if the probe cables break one day.
2) The project/site is effectively dead and the windows driver is not signed. Which means you need trickery to force Win10 into accepting an unsigned driver and you might as well not be able to install the drivers at all one day.
Apart from that, it's pretty nice. The trigger options are pretty limited and weird but at least the SW is reliable and the protocol decoders work reasonably fast (in the 1st SW version I used, they were like 200 times or so slower).

BTW: it's a shame that Ikalogic seems to be incapable of releasing a successor to the ScanaPlus which is discontinued and no longer available. After the planned release date for the ScanaPlus-X has elapsed some months ago, they removed the product page and only mention it as "coming soon".  I always liked my ScanaPlus and still like it despite of some reliability issues but I kinda lost my faith in Ikalogic after releasing one weird product after the other, never fixing the issues in ScanaStudio 2.0 Beta and finally shutting down the forums (some years after crippling them with some fancy Web2.0 nonsense). Actually I kinda assume the company will fold soon. Hope to be wrong though.
Trying is the first step towards failure - Homer J. Simpson
 

Offline Gabri74

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Re: USB Logic Analyzers
« Reply #13 on: October 16, 2017, 05:49:15 pm »
I have a DSLogic (Pro), well actually I have two of them and the hardware is great, but keep two things in mind:
1) There are different versions sold on eBay where some use a weird high density probe connector which means that you can't connect normal jumper wires to the device and are screwed if the probe cables break one day.

By coincidence I was just discussing about different DSLogic versions on the sigrok irc channel few minutes ago. After a boring ebay/aliexpress session this is what I discovered:
- the DSLogic Pro is the same as the DSLogic (original) with adjustable  input levels and are V1 versions
- the Pro seems no longer produced/available
- there are two V2 models with new connector: the Plus and the Basic.
- the Plus has 256MegaBits of SDRAM and is listed on ebay with different titles, like FPGA+Buffer or FPGA+SDRAM for about 100€.
- the Basic model has only 256KiloBits of ram and is listed only as FPGA or SpartanFPGA and is about 60€.
- found also another model priced at 87€ with 16 Mbits of memory... but I think It's a typo

So be careful and read with care all the informations on the listing. Hope it helps.
 

Offline MrW0lf

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Re: USB Logic Analyzers
« Reply #14 on: October 16, 2017, 05:52:36 pm »
This one has 2GigaBits:

Look at views - 29 in 10 days! :palm: Some interesting material in other parts (total 7). I seriously fail to understand world of LAs. For example Sigrok/PulseView seems all the rage architecture wise yet look Google Trends:
https://trends.google.com/trends/explore?date=today%205-y&q=saleae,sigrok,pulseview


« Last Edit: October 16, 2017, 06:06:21 pm by MrW0lf »
 

Offline 0xdeadbeef

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Re: USB Logic Analyzers
« Reply #15 on: October 16, 2017, 06:45:57 pm »
- the Pro seems no longer produced/available
- there are two V2 models with new connector: the Plus and the Basic.
- the Plus has 256MegaBits of SDRAM and is listed on ebay with different titles, like FPGA+Buffer or FPGA+SDRAM for about 100€.
- the Basic model has only 256KiloBits of ram and is listed only as FPGA or SpartanFPGA and is about 60€.
Well, I have an original Plus and a Plus with the new connector. Both have 256MBits of RAM and behave identically.
I prefer the old connector by far as it's much more convenient and robust. Maybe the new one is better suited for high frequencies but I'm not totally convinced it is.
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Offline schmitt trigger

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Re: USB Logic Analyzers
« Reply #16 on: October 16, 2017, 07:40:11 pm »
Guilty? Guilty for what? Nobody forces you to use Saleae software. Sigrok is there for you, free of charge, open source.

On the other hand, if one does indeed use Saleae software, I would purchase the original stuff.
That is what I did.
 

Offline Frddy

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Re: USB Logic Analyzers
« Reply #17 on: October 16, 2017, 09:39:20 pm »
Hey guys I just wanted to chip in regarding the DSLogic.. I recently bought one from ebay which I hope arrives soon.. It should have the 'newest'? style of connectors as in this video:
.

Which looks pretty nice. Atleast that's what I'm hoping for & is what the seller told me.. It was a kit with a separate oscilloscope (microUsb connector appearantly) for 80 USD.. (Right now the same ad is at 180 USD..)

The seller reports "Based on Xilinx Spartan - 6 FPGA + SDRAM", "sampling depth of 16 M * 16 channel"
When I get it I can report back to ye and see what I got.. I'm rather curious myself.. Probably takes another week or two.
« Last Edit: October 17, 2017, 08:38:42 am by Frddy »
 

Offline 0xdeadbeef

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Re: USB Logic Analyzers
« Reply #18 on: October 16, 2017, 10:01:30 pm »
Hm, that's a different style of probes again but the onboard connector looks like the original spacing.
Also the USB controller is different than the original one (Cypress CY7C68013A).
Looks like someone creates a new version every year or so. It's just a shame they put so much more effort in the hardware than in the software.
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Offline smbaker

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Re: USB Logic Analyzers
« Reply #19 on: October 16, 2017, 11:07:11 pm »
I have a DSLogic (Pro), well actually I have two of them and the hardware is great, but keep two things in mind:
1) There are different versions sold on eBay where some use a weird high density probe connector which means that you can't connect normal jumper wires to the device and are screwed if the probe cables break one day.
2) The project/site is effectively dead and the windows driver is not signed. Which means you need trickery to force Win10 into accepting an unsigned driver and you might as well not be able to install the drivers at all one day.

Thanks for the note, I was aware of the two different styles of connectors having seen them in eBay listings (some listings even confusingly showing both styles in the same listing), but I wasn't aware of the driver issues. I don't particularly want to buy a product that's no longer supported and will be giving me endless compatibility problems as Windows marches ever forward.

I think I'm going to go cheap, buy the Saleae clone 16 channel, then once I have my feet wet with that, I can look into something more expensive that will be supported.
 

Offline 0xdeadbeef

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Re: USB Logic Analyzers
« Reply #20 on: October 17, 2017, 12:21:39 am »
There seem to be actually three connector types now where the latest ones look actually the best from the pictures I saw.
It's bad news that the newest version seems to be sold with and without the 256MBit SRAM where the version without SRAM costs as much as the version with SRAM cost one or two years ago.
IMHO removing the buffer RAM is a really bad idea and anybody interested in buying this thing should be really careful not to be tricked into the version without RAM.
And yes the unsigned driver could very soon turn into a showstopper. Actually, as soon as we upgrade to Win10 at work, I won't be able to use the DSLogic there. Even if I could install an unsigned driver driver there (dunno if this will be possible at all in a corporate environment), I guess I won't even try as this will for sure violate the company's code of conduct.
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Offline technogeeky

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Re: USB Logic Analyzers
« Reply #21 on: October 17, 2017, 12:37:03 am »
There seem to be actually three connector types now where the latest ones look actually the best from the pictures I saw.
It's bad news that the newest version seems to be sold with and without the 256MBit SRAM where the version without SRAM costs as much as the version with SRAM cost one or two years ago.
IMHO removing the buffer RAM is a really bad idea and anybody interested in buying this thing should be really careful not to be tricked into the version without RAM.
And yes the unsigned driver could very soon turn into a showstopper. Actually, as soon as we upgrade to Win10 at work, I won't be able to use the DSLogic there. Even if I could install an unsigned driver driver there (dunno if this will be possible at all in a corporate environment), I guess I won't even try as this will for sure violate the company's code of conduct.

I don't know about the driver problems, but I wanted to comment:

1. As to the comment in your previous post, the style of connectors with the individual ground pins per channel are demonstrated to help at high frequencies (as per the video posted above: ). I won't say that his video proves this, it merely demonstrates this.

2. I totally agree. If that unit ships without RAM, then the bandwidth statement becomes totally bogus. There is no way to know what bandwidth you would get with this device in "streaming" mode (because nobody has characterized the overheads), but I bet it's not much. Maybe if this device had a USB3 interface, it could be useful without the RAM.

I don't understand the nomenclature anyway. I don't see a "plus" version at all anywhere on their site.
 

Offline cdev

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Re: USB Logic Analyzers
« Reply #22 on: October 17, 2017, 12:44:16 am »
 Sealae have a very nice product - its built like a tank - and very pretty with its rainbow cables and pod.. The grabber clips it comes with are expensive ones, too. the case is really nice looking.

Was it the first of its kind? No, it wasn't the first of its (Fx) kind.

Was Saelae it the "original" FX based LA? No, not really. 

Was the FX development board for sale before the Saelae Logic was? Yes.

Was it an innovative idea.. Yes. the idea of downloading the program into the hardware was a brilliant idea,
....of some engineer at Cypress.
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Offline Mr. Scram

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Re: USB Logic Analyzers
« Reply #23 on: October 17, 2017, 02:13:12 am »
Sealae have a very nice product - its built like a tank - and very pretty with its rainbow cables and pod.. The grabber clips it comes with are expensive ones, too. the case is really nice looking.

Was it the first of its kind? No, it wasn't the first of its (Fx) kind.

Was Saelae it the "original" FX based LA? No, not really. 

Was the FX development board for sale before the Saelae Logic was? Yes.

Was it an innovative idea.. Yes. the idea of downloading the program into the hardware was a brilliant idea,
....of some engineer at Cypress.
Did Cypress develop their software too? As Dave has shown, a lot of products are let down by the software, even very expensive ones. Saleae seems to do this very well and considering how many have failed, it has taken non-trivial effort to do so.
 

Offline cdev

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Re: USB Logic Analyzers
« Reply #24 on: October 17, 2017, 03:32:03 am »
I use Sigrok (pulseview) and it works great.  Its bright and easy to read. It does the jobs I need it to do.

I don't feel deprived at all.

Sealae have a very nice product - its built like a tank - and very pretty with its rainbow cables and pod.. The grabber clips it comes with are expensive ones, too. the case is really nice looking.

Was it the first of its kind? No, it wasn't the first of its (Fx) kind.

Was Saelae it the "original" FX based LA? No, not really. 

Was the FX development board for sale before the Saelae Logic was? Yes.

Was it an innovative idea.. Yes. the idea of downloading the program into the hardware was a brilliant idea,
....of some engineer at Cypress.
Did Cypress develop their software too? As Dave has shown, a lot of products are let down by the software, even very expensive ones. Saleae seems to do this very well and considering how many have failed, it has taken non-trivial effort to do so.
« Last Edit: October 17, 2017, 10:01:58 pm by cdev »
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