Choosing a logic anaylser - will my expectations lead me to bankruptcy? - Page 1
Forum section: electronics / testgear

author: eTobey
author_rank: Super Contributor
timestamp: October 26, 2024, 08:02:43 am
content: 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 FDCANThose 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 triggersIt 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?

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2024, 09:04:21 am
content: 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/ArduinoThe 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_hardwareThe 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.

author: BennoG
author_rank: Frequent Contributor
timestamp: October 26, 2024, 09:29:28 am
content: A picoscope with logic analyzer will do the job and also all the decoding you want.Benno

author: Whales
author_rank: Super Contributor
timestamp: October 26, 2024, 09:50:27 am
content: Quote from: eTobey on October 26, 2024, 08:02:43 am25V logic levels, or 3.3V logic levels with occasional 25V mess on top?

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2024, 10:22:13 am
content: 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.

author: NE666
author_rank: Frequent Contributor
timestamp: October 26, 2024, 10:29:33 am
content: Quote from: eTobey on October 26, 2024, 08:02:43 amIn 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

author: Sorama
author_rank: Frequent Contributor
timestamp: October 26, 2024, 10:35:51 am
content: Have a look athttps://www.activefirmwaretools.com/Input voltage is limited though :6V

author: PlainName
author_rank: Super Contributor
timestamp: October 26, 2024, 01:04:10 pm
content: Quote from: Sorama on October 26, 2024, 10:35:51 amThat 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.

author: nctnico
author_rank: Super Contributor
timestamp: October 26, 2024, 01:25:03 pm
content: Quote from: NE666 on October 26, 2024, 10:29:33 amThis 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.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2024, 01:40:37 pm
content: 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.

author: UniSoft
author_rank: Frequent Contributor
timestamp: October 26, 2024, 02:20:35 pm
content: Take a look DSLogichttps://www.dreamsourcelab.com/

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2024, 02:39:39 pm
content: 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".

author: BillyGo
author_rank: Contributor
timestamp: October 26, 2024, 03:17:47 pm
content: Quote from: RoGeorge on October 26, 2024, 02:39:39 pmThe 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.

author: ebastler
author_rank: Super Contributor
timestamp: October 26, 2024, 03:40:53 pm
content: Quote from: BillyGo on October 26, 2024, 03:17:47 pmIn 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?

author: tggzzz
author_rank: Super Contributor
timestamp: October 26, 2024, 03:47:46 pm
content: If an LA doesn't come with decent grabbers, then have a look at the prices for Tek and HP grabbers on fleabayOne way of reducing the expenditure is to think carefully about how you can debug a circuitwithoutan 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 transitionsignores everything except when specific signals are asserted, e.g. a chip select or write enableThat will enable you to isolate read/writes to specific i/o devices, and to only see the UUT's FSMstateswithout irrelevant gaps where nothing happens.You can get far more complex filtering and triggering, but the above two cover 90% of use cases.

author: nctnico
author_rank: Super Contributor
timestamp: October 26, 2024, 03:55:59 pm
content: Quote from: tggzzz on October 26, 2024, 03:47:46 pmTrue, 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.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: October 26, 2024, 04:17:16 pm
content: Quote from: Sorama on October 26, 2024, 10:35:51 amLooks 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 Tools43480 Corte RialtoTemecula CA 92592 USAhttps://www.activefirmwaretools.com/aboutSeem 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

author: Sorama
author_rank: Frequent Contributor
timestamp: October 26, 2024, 04:21:54 pm
content: What a weird reaction.It is a small (?) engineering company.Nothing wrong with that.

author: tggzzz
author_rank: Super Contributor
timestamp: October 26, 2024, 04:22:42 pm
content: Quote from: nctnico on October 26, 2024, 03:55:59 pmOh, yes indeedI 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 ithasn'ttriggered. The ability to ignore crap isveryimportant.But this thread is about what you can get away with, so I think my 90% point is useful in this contexr.

author: m k
author_rank: Super Contributor
timestamp: October 26, 2024, 07:04:07 pm
content: Quote from: eTobey on October 26, 2024, 08:02:43 amYou 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.

author: NE666
author_rank: Frequent Contributor
timestamp: October 27, 2024, 10:02:59 am
content: 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.

author: abeyer
author_rank: Frequent Contributor
timestamp: October 27, 2024, 09:08:45 pm
content: Quote from: NE666 on October 27, 2024, 10:02:59 amI 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.

author: NE666
author_rank: Frequent Contributor
timestamp: October 28, 2024, 10:55:46 am
content: Quote from: abeyer on October 27, 2024, 09:08:45 pmFeels like a solution in search of a problem to me. YMMV.

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 28, 2024, 02:41:57 pm
content: Quote from: NE666 on October 27, 2024, 10:02:59 amThe digital discovery is only 5V, the analog one is -25 to +25

author: RAPo
author_rank: Super Contributor
timestamp: October 28, 2024, 03:04:55 pm
content: Does it have to be a separate LA?TheMICSIG STO2002could 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 widthAnd 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.

author: egonotto
author_rank: Super Contributor
timestamp: October 28, 2024, 03:10:08 pm
content: Quote from: PA0PBZ on October 28, 2024, 02:41:57 pmHello,no for the digital inputs of the Analog Discovery 2: “Input and output pins are LVCMOS3V3. Inputs are 5V tolerant. Overvoltage up to ±20V is supported.”Best regardsegonotto

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 28, 2024, 03:37:57 pm
content: Quote from: egonotto on October 28, 2024, 03:10:08 pmYou are correct, the spec -25/-25V on the front page is for the analog (scope) channels, even for the discovery 3.

author: iMo
author_rank: Super Contributor
timestamp: October 28, 2024, 03:44:46 pm
content: A simple resistor for the input protection is not enough for the +/-25V, imho.Resistor should be large value (because the internal on-chip ESD clamping diodes are for 5mA max usually) and that will limit the BW/response.The Analog Discovery 2 is using 220ohm PTC and additional 2 external DB3S406F fast 40V/75mA clamping diodes at its digi inputs.PS: Some 15y back I was an early adopter of the Dangerous Prototypes first larger product - the Open Bench Logic Sniffer LA - still with almost alpha fw for the fpga and pic mcu and pc app at that time. Lot of fun with finetuning of the fw and pc app afterwards (I think we went from 50MHz sampling rate up to 200MHz !!).. $50 incl. shipping, I was using it a lot, well but today rather a toy..Quotefyi -http://dangerousprototypes.com/docs/Open_Bench_Logic_Sniffer.. the page was last modified in Jan2015..Advanced HP16550 triggers:http://dangerousprototypes.com/docs/Logic_Analyzer_core:_Introduction

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 28, 2024, 06:33:00 pm
content: I quite like my Kingst LA2016. On the box is written inputs can withstand from -50V to +50V and it works with Sigrok / Pulseview. Kingst also has support for Linux, so I could even use the original software, but I quite like Pulseview. You do need a pretty recent Pulseview version for the Kingst to work properly I now have: 0.5.0-git-9b8b734.

author: eTobey
author_rank: Super Contributor
timestamp: October 28, 2024, 10:13:34 pm
content: I have now looked at the Dslogic Plus. It looks like it has a nice trigger setup, where one could really get creative.There is not a big community, and there was some license problems, but i have not read any bad things about it. The manual is very detailed, much more than the Kingst LA2016 for example. Its also about 40€ cheaper. The probes look good too.The software is maintained.

author: ebastler
author_rank: Super Contributor
timestamp: October 30, 2024, 05:22:17 am
content: Quote from: ebastler on October 26, 2024, 03:40:53 pm@BillyGo -- I was hoping to get more details from you on the DSView software. What do you dislike about it, where is the "huge disaster" in your opinion?