Choosing a logic anaylser - will my expectations lead me to bankruptcy?

[eTobey]

Hi,

i need a logicanalyser, since debugging has become a bit more involving. I have read a bit, and i have come to the following requirements:
- It should do about 5Mhz
- It would be nice, if the inputs can withstand 25V
- Input of 1MOhm
- Decoding of I2C, UART, SPI and FDCAN

Those are not required, but would be really useful:
- Graphical representation of dutycycle, pulse width
- A output would be nice to sync with a scope
- Advanced triggers


It can be a USB device or a portable one.

I have seen a few cheap ones only go to 5V. I have the feeling i have to dive deep into the three digit price range with these expectations? Which points would be higher price range products anyway?

[RoGeorge]

Unless you need high speed (10MHz+), any Arduino board can act as a logic analyzer.  Can even do analog (oscilloscope like waveforms) with its ADC:  http://sigrok.org/wiki/Arduino

The software most commercial LA are using is based on Sigrok (command line, has all the decoders and all the advanced triggers in the world, plus you can write your own, can stack different decoders, etc.) + Pulseview (the GUI to control sigrok).  Both are free, open source, and working on any OS.

If you don't have any Arduino (an Arduino nano is ~$2), or if you need other logic levels than 5V, you may find another devboards, or other lab instruments that is supported by sigrok, see the sigrok upported HW list:  https://sigrok.org/wiki/Supported_hardware

The Pulseview GUI to handle the waveform is the same for all devices.  Most other proprietary LA are using the same Pulseview with different theme customization.

[BennoG]

A picoscope with logic analyzer will do the job and also all the decoding you want.

Benno

[Whales]

- It would be nice, if the inputs can withstand 25V

25V logic levels, or 3.3V logic levels with occasional 25V mess on top?

[RoGeorge]

Withstand is about occasional voltage.

A series resistor (to limit the max current at less than 5mA or so) in series with each digital input would do the trick, because the DI typically have 2 protection diodes, one to Vcc and one to GND.

[NE666]

- A output would be nice to sync with a scope
- Advanced triggers

Which points would be higher price range products anyway?

In my experience, it's at these two points that cost starts to increase in orders of magnitude. Especially for sophisticated triggering requirements.

HP / Tek benchtop units excel here but are still stupidly expensive on auction sites given their age (imho). Plus, you need to be prepared to sacrifice a lot of bench space for them. And maybe live with embedded Windows XP..

The best compromise I found was the DigiView range from TechTools. The software is excellent and that, again in my opinion, really makes any given LA hardware truly useful or not. Sadly, the ancient unit I bought didn't live long but whilst it did, I couldn't have a more functional LA for under 200USD. Their new units start at 600USD before taxes and shipping.

You can download their software for free and use it in demo mode, to see what you're missing with everything else. And of course, decide whether you're prepared to pay the premium for Advanced Triggering.

https://tech-tools.com/trigger-cfg.html

[Sorama]

Have a look at
https://www.activefirmwaretools.com/

Input voltage is limited though :6V

[PlainName]

Have a look at
https://www.activefirmwaretools.com/

Input voltage is limited though :6V

That appears to be made by the chap that made the EE101 debugger which, if you invested your money and time in it, might leave a bad taste since it is now abandoned. This one looks good, but then so did the other, and I would always be wondering when he might abandon this and start another.

[nctnico]

- A output would be nice to sync with a scope
- Advanced triggers

Which points would be higher price range products anyway?

In my experience, it's at these two points that cost starts to increase in orders of magnitude. Especially for sophisticated triggering requirements.

HP / Tek benchtop units excel here but are still stupidly expensive on auction sites given their age (imho). Plus, you need to be prepared to sacrifice a lot of bench space for them. And maybe live with embedded Windows XP..

The best compromise I found was the DigiView range from TechTools. The software is excellent and that, again in my opinion, really makes any given LA hardware truly useful or not. Sadly, the ancient unit I bought didn't live long but whilst it did, I couldn't have a more functional LA for under 200USD. Their new units start at 600USD before taxes and shipping.

You can download their software for free and use it in demo mode, to see what you're missing with everything else. And of course, decide whether you're prepared to pay the premium for Advanced Triggering.

https://tech-tools.com/trigger-cfg.html

This looks very interesting indeed and seems to have a sophisticated trigger system. A sequencer based trigger system is what sets a real logic analyser apart from the many simplistic logic analysers. I'm still not clear on the memory depth though. It says it has 128Mbit of memory. So without compression, this 100Mbit seems to be shared among all the channels.

While you can certainly buy a good Tek or Agilent logic analyser for a similar price (*), I would take a long look at the tech-tools unit first.

* Asking prices on Ebay can be insane so they are not a good indicator of actual selling prices.

[RoGeorge]

Sigrok can do sequence triggering too, and mixed analog + digital signals display, so unless the sampling speed needs to be very high, an Arduino + sigrok + Pulseview might probably beat dedicated LA instruments.

Then, at $2 the entire device, who cares about protecting the inputs against all possible wrong connections.  If you broke it, replace the entire $2 hardware, and be more careful next time. 

[UniSoft]

Take a look DSLogic
https://www.dreamsourcelab.com/

[RoGeorge]

I have a DSLogic, but it's rather expensive (by comparison with the typical dedicated $5-10 LA USB dongle with 8channels/24MHz, like the Saleae clones).

DSLogic has an FPGA as hardware, and adjustable logic levels, and can go up to many hundreds of MSa/s (mine goes up to 400MSa/s IIRC).  Beware that the max speed for most LA is given when only 2 or 4 inputs are used.  No matter the brand name, usually the max specified speed is not possible on all the available inputs at the same time.

The software for DSLogic is as usual, a customized sigrok + Pulseview packed together as "DSView".

[BillyGo]

I have a DSLogic, but it's rather expensive (by comparison with the typical dedicated $5-10 LA USB dongle with 8channels/24MHz, like the Saleae clones).

DSLogic has an FPGA as hardware, and adjustable logic levels, and can go up to many hundreds of MSa/s (mine goes up to 400MSa/s IIRC).  Beware that the max speed for most LA is given when only 2 or 4 inputs are used.  No matter the brand name, usually the max specified speed is not possible on all the available inputs at the same time.

The software for DSLogic is as usual, a customized sigrok + Pulseview packed together as "DSView".

The old version of DSLogic with Xilinx FPGAs worked almost perfectly with the original PulseView.

On DSView, they tried to make the UI look similar to Saleae, but it was a huge disaster.

[ebastler]

On DSView, they tried to make the UI look similar to Saleae, but it was a huge disaster.

In which respect? I have the DSLogic on my wishlist, have played with DSView in demo mode and found it quite neat. Can you elaborate on its shortcomings, or link to reviews which do so?

[tggzzz]

If an LA doesn't come with decent grabbers, then have a look at the prices for Tek and HP grabbers on fleabay

One way of reducing the expenditure is to think carefully about how you can debug a circuit without an LA. Use a scope to assure signal integrity, then flip to printf() or a protocol analyser.

If you can afford more than the simple "grab everything and let the user delve for useful information on a PC", then it it worth getting something that does the bare minimum data reduction:

• ignores everything except during UUT clock transitions
• ignores everything except when specific signals are asserted, e.g. a chip select or write enable

That will enable you to isolate read/writes to specific i/o devices, and to only see the UUT's FSM states without irrelevant gaps where nothing happens.

You can get far more complex filtering and triggering, but the above two cover 90% of use cases.

[nctnico]

You can get far more complex filtering and triggering, but the above two cover 90% of use cases.

True, but if you need the extra 10%, having a logic analyser which can go the extra mile it worth it's weight in gold. I have used the sequential triggering system in various Tektronix logic analysers I have owned over the years to find extremely hard to trace problems in very complex systems.

[DaneLaw]

Have a look at
https://www.activefirmwaretools.com/

Input voltage is limited though :6V

Looks questionable that site, not least with all these massive brands, and the wording "Trusted by" SpaceX, Meta, Teledyne, Microsoft BAE, US Army etc.. all brands that are usually very sparse on letting other companies use their brand-credentials & logos to create sale incentives (*consumer "confidence" from seeing well-known brands advocating, and "trusted by" to endorse a given item)

if you look up their address.

Join us..
Active Firmware Tools
43480 Corte Rialto
Temecula CA 92592 USA
https://www.activefirmwaretools.com/about

Seem to be for a private empty house in a residential area, been on the market for quite some time with various on / off.
https://www.zillow.com/homedetails/43480-Corte-Rialto-Temecula-CA-92592/18174539_zpid/

Sure..
https://tinyurl.com/yrrdh9kr

[Sorama]

What a weird reaction.

It is a small (?) engineering company.
Nothing wrong with that.

[tggzzz]

You can get far more complex filtering and triggering, but the above two cover 90% of use cases.

True, but if you need the extra 10%, having a logic analyser which can go the extra mile it worth it's weight in gold. I have used the sequential triggering system in various Tektronix logic analysers I have owned over the years to find extremely hard to trace problems in very complex systems.

Oh, yes indeed

I have an HP/Agilent 1682, and it is delightful to leave it running for a day with a trigger set to find a fault, and to return to find it hasn't triggered. The ability to ignore crap is very important.

But this thread is about what you can get away with, so I think my 90% point is useful in this contexr.

[m k]

Hi,

i need a logicanalyser

You have clear hardware and software specific requirements.

Can you make a pod that does other voltages?

What are special triggers, more parallel or serial?
If parallel you can add them to your DIY pod, but basic software is probably not going to bend.
(possible timing difference)

How many channels?
8 and 16 are some limits, after that the situation changes.

[NE666]

https://www.activefirmwaretools.com/

Putting the nature of that company and its leadership aside, I struggle to see what you're getting with that product vs Digilent's much better known (and I'll hazard, much better supported) Analogue Discovery 3.

And if you don't require mixed signal, the Digital Discovery makes even more sense.

[abeyer]

Putting the nature of that company and its leadership aside, I struggle to see what you're getting with that product vs Digilent's much better known (and I'll hazard, much better supported) Analogue Discovery 3.

And if you don't require mixed signal, the Digital Discovery makes even more sense.

I think their software, at least, looks interesting, and seems to be targeting much more the software/firmware side of things as their audience. The probe hardware itself isn't particularly impressive, but I haven't seen anyone else do the fairly seamless correlation between logic traces and debug logs and source code it can. Is that worth the price...  If nothing else I hope to see some of those features land in sigrok and others.

[NE666]

seamless correlation between logic traces and debug logs and source code it can. Is that worth the price

Feels like a solution in search of a problem to me. YMMV.

[PA0PBZ]

And if you don't require mixed signal, the Digital Discovery makes even more sense.

The digital discovery is only 5V, the analog one is -25 to +25

[RAPo]

Does it have to be a separate LA?
The MICSIG STO2002 could probably do what you want (the input is by standard BNC probes -not a special LA-probe-)
it has all the decoding you've asked for.

There is a graphical representation of duty cycle, pulse width
And the output would be nice to sync with a scope baked in ;-).

As for the price, it is below 4 digits, you get LA and oscilloscope functionality.