Sigrok & $10 Logic Analyzer from Ali Express

[JenniferG]

I just watched the following video of a guy using a $10 Saele clone 8 channel Logic Analyzer (24mhz) along with Sigrok.

The Sigrok software / Pulse View looks really nice.  I can't wait to try it out when I get my used $100 Thinkpad T450

Should I grab something like this for $10 from Aliexpress? It's only 24mhz though. This video is 5 years old.  But it's plenty fast for things like Arduino, since it only runs at 16 Mhz.



Are there better ones for the same money now?  I really like the idea of just $10. Or even $20.

[JenniferG]

If I got something like this, woudl it replace the need for serial decoding features on a scope?  I am looking to buy a 4 channel scope.  Should I not be concerneda bout the logic features of a scope since I can get them with a logic analyzer?

[Fungus]

Which 4-channel 'scope doesn't have serial decoders? 

For $10 you could get one of these as well. They work in different ways and can complement each other...

[DavidAlfa]

A scope isn't a proper machine to decode data.
Perhabs for few bytes, seeing a single event, but not for large transfers.
That cheap clone will be more useful for that, i.e. capturing 30 seconds and then later on analyze what's going on.
24MHz is plenty for a lot of things.

You can also get a fx2 board which mostly the same, it'll work at 24MHz(8ch) or 12MHz (16ch).
However it lacks a buffer, so it'll be 3.3V max.
https://a.aliexpress.com/_EvEdTh7

[JenniferG]

Which 4-channel 'scope doesn't have serial decoders? 

For $10 you could get one of these as well. They work in different ways and can complement each other...

I read that some 4 channel scopes serial decoding is almost useless.  But maybe I won't need 4 channel scope at all if I get this logic analyzer. I am into audio/synth electronics.  All I have currently is Tektronix 2225 and it can't capture single shot stuff.  So I need some sort of digital storage scope.  2 channels might even be sufficient.

[pcprogrammer]

I read that some 4 channel scopes serial decoding is almost useless.  But maybe I won't need 4 channel scope at all if I get this logic analyzer. I am into audio/synth electronics.  All I have currently is Tektronix 2225 and it can't capture single shot stuff.  So I need some sort of digital storage scope.  2 channels might even be sufficient.

For calibrating analog polyphonic synths 4 channels can be very handy. Means you can check multiple oscillators and filter plus amplifier outputs at once to see if the signals are correct. But it depends on your budget of course what you can get.

The cheap 8 channel 24MHz logic analyzer is very handy when working on microcontrollers. Easy to capture lots of data on the PC and then examine it. For real time checking the signals a scope is still better though. I have and use both

[Bicurico]

The cheap chinese clones of Saleae do work and are recognized by the Saleae software. They constitue a clone of the obsolete 8 port/24MHz model.

However, as you can guess it, paying 10$/£/€ for a cloned device will pay exactly zero to Saleae who developed the software! Not exactly fair use.

Of course you can convince yourself that you are just going to use the device with Sigrok open source software, still you are sponsoring a cloned HW/FW design.

I am not judging, I don't work for Saleae, but I think this aspect should not be forgotten.

Using oscilloscopes for serial communication logging does not remotely work as nicely as with a logic analyser - at least on the Rigol DS1000Z!

[DavidAlfa]

Nope, the software is entirely made by Sigrok (fx2lafw).
Those MCUs are rom-less, they load the firmware either from external eeprom (not this case) or from the usb port (Pulseview loads it).

Also I'm pretty most Saleae firmware came from existing demo projects, it's basically an endless transfer loop with some control commands:
https://www.infineon.com/cms/en/design-support/software/code-examples/usb-controllers-code-examples/usb-hi-speed-code-examples/

[JenniferG]

The cheap chinese clones of Saleae do work and are recognized by the Saleae software. They constitue a clone of the obsolete 8 port/24MHz model.

However, as you can guess it, paying 10$/£/€ for a cloned device will pay exactly zero to Saleae who developed the software! Not exactly fair use.

Of course you can convince yourself that you are just going to use the device with Sigrok open source software, still you are sponsoring a cloned HW/FW design.

I am not judging, I don't work for Saleae, but I think this aspect should not be forgotten.

Using oscilloscopes for serial communication logging does not remotely work as nicely as with a logic analyser - at least on the Rigol DS1000Z!

Yeah I realize that and appreciate Saleae.  But like you say this is a clone of a discontinued model and I'm using openSource software with it.  Also I am not into electronics to make any money but am a poor hobbyist.  I don't make any money with it.

Btw, of all the PC's you've bought in the past did you feel any guilt?  Because it was IBM's design and people starting cloning them all the since the IBM PC XT.

[RoGeorge]

If I got something like this, woudl it replace the need for serial decoding features on a scope?  I am looking to buy a 4 channel scope.  Should I not be concerneda bout the logic features of a scope since I can get them with a logic analyzer?

Decoding in the oscilloscope is a nice to have, but don't agonize too much about it.  A $10 LA can do it better for longer acquisition and reverse engineering.  Also, many oscilloscopes can be used with Sigrok, so the same software and the same plethora of decoders (sigrok has way more decoders than any oscilloscope, and custom decoders can be added any time).

In my case, I've used the decoding features only a couple of times in the last years, mostly for demonstrative /didactic reasons.  I also have a LA which I never use in practice because it's easier to make a change in code and observe if it works than to hang the probes of an LA, then start acquiring, and decoding, and fiddling with triggering and so on.

Hooking an LA and decoding only makes sense when the data sent is unknown, e.g for reverse engineering.
When building things or writing software, an LA it is not needed at all.
Protocol decoders in an oscilloscope is nice to have, but not critical.

[Bicurico]

Yeah I realize that and appreciate Saleae.  But like you say this is a clone of a discontinued model and I'm using openSource software with it.  Also I am not into electronics to make any money but am a poor hobbyist.  I don't make any money with it.

I am not judging, I don't work for Saleae, but I think this aspect should not be forgotten.

Btw, of all the PC's you've bought in the past did you feel any guilt?  Because it was IBM's design and people starting cloning them all the since the IBM PC XT.

I don't think the comparison with IBM is in any way relevant or comparable.

Nope, the software is entirely made by Sigrok (fx2lafw).
Those MCUs are rom-less, they load the firmware either from external eeprom (not this case) or from the usb port (Pulseview loads it).

Still, it was Salaea's idea to use the MCU to build a logic analyzer. That was shamelessly stolen.

I don't care nor judge anyone going that route and I am not a saint, either. As mentioned, just wanted to point it out.

[Fungus]

I read that some 4 channel scopes serial decoding is almost useless.

"almost" 

But maybe I won't need 4 channel scope at all if I get this logic analyzer.

The price difference between 2 and 4 channels isn't much these days, I'd get 4 channels if possible.

But if not: A modern 2-channel DSO will still be a huge step up from the Tek 2225.

[Fungus]

A scope isn't a proper machine to decode data.
Perhabs for few bytes, seeing a single event, but not for large transfers.
That cheap clone will be more useful for that,

But a cheap logic analyzer won't show you if the data signal is malformed or not.

[DavidAlfa]

Sure it will, showing a framing error when running a decoder.

[DavidAlfa]

Still, it was Salaea's idea to use the MCU to build a logic analyzer. That was shamelessly stolen.

Maybe you wanted to mean: Saleae took the idea from Cypress docs and made an incredible profit from it (from $5 to $149, not even Apple got so far lol)

https://www.infineon.com/dgdl/Infineon-AN66806_Getting_Started_with_EZ-USB_FX2LP_GPIF-ApplicationNotes-v09_00-EN.pdf?fileId=8ac78c8c7cdc391c017d0735e06f5911

[JenniferG]

I bought this one from Amazon for $10.99 plus tax.

https://www.amazon.com/gp/product/B099WJQV67

[Bicurico]

Point taken. I did not know that.

[markone]

I bought this one from Amazon for $10.99 plus tax.

https://www.amazon.com/gp/product/B099WJQV67

It could be like this one : http://sigrok.org/wiki/VKTECH_saleae_clone

Take in consideration that these clones have fixed voltage threshold and do not handle correctly signal over 5V in input, where the stage is a simple series resistor in the order of 100-330 ohms followed by a high value pullup resistor (usually 100Kohms), some models have also a small value capacitor toward ground and /or clamping diodes and sometime is present a logic buffer like HC245 in between inputs and FX2 chip.

So, if you detach USB connector from the "dongle" it will absorb current from input digital signal lines trying to supply the LA ... 

Apart that its worth the money.

To be honest Sigrok based Pulseview is a very minimal LA application, it lacks some important features like trigger on serial content, that means a lot for serious debugging.

Current Saleae Logic versione does it and I'm afraid that once you've tried it (Logic) you'll never go back (Pulseview), like all the all hobbyists in this forum 

[JenniferG]

Current Saleae Logic versione does it and I'm afraid that once you've tried it (Logic) you'll never go back (Pulseview), like all the all hobbyists in this forum 

I can't afford $500 for a logic analoyzer though.  That's their cheapest. 

[markone]

Current Saleae Logic versione does it and I'm afraid that once you've tried it (Logic) you'll never go back (Pulseview), like all the all hobbyists in this forum 

I can't afford $500 for a logic analoyzer though.  That's their cheapest.

I'm afraid you didn't understand : you will be able to use your purchase with Logic software, out of the box.

This is the reason why we call them "clones".

[2N3055]

I bought this one from Amazon for $10.99 plus tax.

https://www.amazon.com/gp/product/B099WJQV67

It could be like this one : http://sigrok.org/wiki/VKTECH_saleae_clone

Take in consideration that these clones have fixed voltage threshold and do not handle correctly signal over 5V in input, where the stage is a simple series resistor in the order of 100-330 ohms followed by a high value pullup resistor (usually 100Kohms), some models have also a small value capacitor toward ground and /or clamping diodes and sometime is present a logic buffer like HC245 in between inputs and FX2 chip.

So, if you detach USB connector from the "dongle" it will absorb current from input digital signal lines trying to supply the LA ... 

Apart that its worth the money.

To be honest Sigrok based Pulseview is a very minimal LA application, it lacks some important features like trigger on serial content, that means a lot for serious debugging.

Current Saleae Logic versione does it and I'm afraid that once you've tried it (Logic) you'll never go back (Pulseview), like all the all hobbyists in this forum 

Sealae does not trigger from protocol in hardware sense. They keep running fast stream and filter in software until they see packet that fits filter. It is very clever but not real triggering. For slow protocols it ends up being same, though.

[JenniferG]

Sealae does not trigger from protocol in hardware sense. They keep running fast stream and filter in software until they see packet that fits filter. It is very clever but not real triggering. For slow protocols it ends up being same, though.

Perhaps Pulse View will be updated at some point to be able to do this?

[colorado.rob]

Sealae does not trigger from protocol in hardware sense. They keep running fast stream and filter in software until they see packet that fits filter. It is very clever but not real triggering. For slow protocols it ends up being same, though.

Perhaps Pulse View will be updated at some point to be able to do this?

Be the change you wish to see in the world.

[markone]

Sealae does not trigger from protocol in hardware sense. They keep running fast stream and filter in software until they see packet that fits filter. It is very clever but not real triggering. For slow protocols it ends up being same, though.

Perhaps Pulse View will be updated at some point to be able to do this?

Not that i know and I wouldn't hold my breath waiting for them to do it.

If this function is a must for you, you have two choices : use your clone with Logic software, up to certain baud rate it will work like a charm if you have a decent PC, otherwise spend some more money in something that has local buffer and implement trigger mechanism at hardware level.

I recently put my bet on DSlogic Plus (that now is on its way from China) because its producer "promises" that it works with a multi stage protocol trigger implemented at FPGA level.

[mwb1100]

I recently put my bet on DSlogic Plus (that now is on its way from China) because its producer "promises" that it works with a multi stage protocol trigger implemented at FPGA level.

Please post about how well it works after you've tried it out.