inexpensive USB logic analyzers for beginners - Page 1
Forum section: electronics / testgear

author: drakke
author_rank: Regular Contributor
timestamp: January 10, 2015, 07:08:40 am
content: I am a beginner building a 8088-based single board computer. I am also taking an embedded electronics course and am interested in microcontrollers. I have bought an oscilloscope already.Are any of these of value? There is no manufacturer/brand name to search the forums.Which one would be the best value?8 channel 24MHz -http://www.ebay.com/itm/Compatible-Saleae-USB-Logic-24MHz-8Ch-Logic-Analyzer-ARM-FPGA-/251712619461?tfrom=251716074406&tpos=top&ttype=coupon&talgo=undefined16 channel 250MHz -http://www.ebay.com/itm/100MHz-16CH-250MHz-8CH-PC-USB-Logic-Analyzer-With-Support-I2C-SPI-UART-And-PWM-/251716074406?pt=LH_DefaultDomain_0&hash=item3a9b727ba634 channel 125MHz -http://www.ebay.com/itm/34CH-100MHz-125MHz-PC-USB-Logic-Analyzer-Support-I2C-SPI-UART-And-PWM-/261659633171?tfrom=251716074406&tpos=top&ttype=coupon&talgo=undefinedSorry - I just found a thread on this but I cannot delete this post.https://www.eevblog.com/forum/testgear/34ch-chinese-la/Thanks

author: dds737
author_rank: Contributor
timestamp: January 11, 2015, 12:44:08 pm
content: http://www.jwandrews.co.uk/2011/12/saleae-logic-analyser-clone-teardown-and-reprogramming/Just search 'saleae logic analyser clone review' and you will get lot of hits on google.com

author: nctnico
author_rank: Super Contributor
timestamp: January 11, 2015, 12:59:13 pm
content: Why didn't you buy an oscilloscope with digital channels?

author: aviphysics
author_rank: Contributor
timestamp: January 12, 2015, 03:22:26 am
content: Quote from: nctnico on January 11, 2015, 12:59:13 pmSpeaking of which, how do these USB logic analyzers compare to those built into the Rigol MSO1000 scopes?

author: e_60
author_rank: Contributor
timestamp: January 12, 2015, 05:05:05 am
content: Quote from: aviphysics on January 12, 2015, 03:22:26 amThe MSO1000Z does not compare at all from my (short) experience. Do some searching on here about decoding from trace vs memory i.e. DataSrc = Trace. Depending on what you are trying to decode, you can only look at a very small amount at any given time, you cannot actually decode what is captured in memory. Nearly useless in my opinion. Certainly does not justify the addon license cost.I am now using an MSO2072A for my decoding on SPI and I am quite happy so far. Some tasks do require pulling out a dedicated logic analyzer, but mostly I can use the MSO. If you cannot afford both an MSO scope and analyzer, I would lean towards getting a dedicated logic analyzer.On the topic of Saleae clones, my opinion is that it is unethical to purchase one and use the official Saleae software. As for the quality of the hardware of the clones, unknown to me, but I would suspect not good. The last thing I want to be doing is debugging / second guessing the test equipment I am trying to use to debug my own work. I am also against the various hacks to unlock all the features of of the scopes though, and it seems many people here do not share that view, which I am surprised from a community that seems to have many people creating products and expecting to be compensated for their work.

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: January 12, 2015, 05:20:49 pm
content: Saleae is a toy good for SPI and I2C low wire count stuff. You need something more suitable for hooking to a cpu and its bus.If you need an LA for helping build/debug your 8088 board, you need 8 lines for data, 8 lines for bus, bunch of lines for the control pins (mem read/write, io, clk, status, sso,s2,s1,s0, hold, den etc.).trying to monitor all this with Saleae is a bad idea, its still a 40 pin dip chip for a reason.

author: aviphysics
author_rank: Contributor
timestamp: January 13, 2015, 02:43:51 am
content: Quote from: e_60 on January 12, 2015, 05:05:05 amHmmm. MSO1074z vs MSO2072a price difference is $380. Already decided to ditch the "-S" on the MSO1074z and get a dedicated signal generator. Is the 2000 series that much of a step up that it is worth the extra money? I very much wish there was something between the 2000 series and 4000 series. Here's to hoping that the march in declining scope prices continues.Does the MSO2000 series lose an analog channel when you use the LA? That would be a pretty big deal to me.I mainly wanted the LA for troubleshooting the digital I/O pins on microcontrollers. Just making sure they are all behaving how I think they should. Maybe a little bit of i2C.Looking through some of the USB LA, it looks like I could get a pretty sweet low end USB LA for $380.

author: Lightages
author_rank: Unknown
timestamp: January 13, 2015, 04:04:06 am
content: There seems to be a real lack of good information and comparisons of USB logic analyzers. I for one would like to see a good comparison of different analyzers from someone who KNOWS what they are talking about.I have thought of doing something but I have a year long back log of videos to do and I will be starting this week with my back log. I am definitely not the person to do a good review/comparison of logic analyzers but t looks like by the time I get done with my back log there still won't be anything good for most people to help decide.Dave did a commentary on USB logic analyzers but it hardly covers what is available today nor is it any kind of review. Maybe someone who has the time, lots of time, can get on something soon. If not, look for my review in the far future.

author: DIPLover
author_rank: Regular Contributor
timestamp: January 13, 2015, 04:56:04 am
content: For debugging a computer system, what you need is STATE analysis where you give your system clock to the analyzer to synchronize on so you can acquire on every clock cycle. Saleae-type analyzers don't do it. They are useless for your purpose.They are also EXPENSIVE, especially with the new pricing.For an 8bit system, you need at least a 32/34 channels LA.The 8088 has 40 pins, 37 of which you might want to monitor at some point, and certainly the address (19 pins) and Data (8 pins).I got my first LA, an HP 1663C 34 channel that does 100MHz STATE analysis on all channels (and up to 500MHz timing analysis) for 79$ plus shipping on eBay. It beats the living shit out of any USB LA under a grand or two for retro-computer development.The Saleae does have a very nice software interface and will decode your serial data however. I just regret buying mine (and losing 90$ on re-sell) without knowing that an LA without State analysis was even a thing...Also the acquisition speed they quote (100MHz on logic16) is only available when you use 2 channels... at full 16 channels that dropped to 12.5MHz. Since in Timing analysis mode you must oversample your signals, don't expect to debug anything faster than 2-3MHz with the full channel count.

author: coppice
author_rank: Super Contributor
timestamp: January 13, 2015, 05:17:18 am
content: Quote from: DIPLover on January 13, 2015, 04:56:04 amWithout state analysis its just a scope with very poor vertical resolution.

author: Lightages
author_rank: Unknown
timestamp: January 13, 2015, 06:43:47 am
content: So after looking at many offerings of logic analyzers from different companies, it is very apparent that there is no clear easy choice. You can pick from good software, high sample rate, variable logic voltages, internal buffer, PC streaming, compression, protocols, price, etc. These are many variables and none are clearly defined without many hours of research.It seems to me that software rules over everything else because if it doesn't work there is nothing to see. Next would be your actual need when it comes to the hardware. If you want to view really high speed stuff then you can forget anything lower than $400. If you can live with below 100MHz sample rate then you need to worry about capture length and blah blah blah.I don''t think there is an answer. Buy something that decodes what you are working on right now. If you need better you will know.Something like this has been recommended before and might have the option for modifications:http://www.nkcelectronics.com/zeroplus-lap16032u-logic-ana16032.htmlThe Saleae stuff has been recommended and probably will meet most peoples needs. Buy what you need from them,I have also eyed this one many times but the low buffer length has always put me off:http://www.pctestinstruments.com/index.htmIMHO I would avoid all the clone crap as it will probably just let you down. HAcking around to make something work is a pain and detracts from the actual work.

author: pickle9000
author_rank: Super Contributor
timestamp: January 13, 2015, 07:18:54 am
content: If you are looking for super cheap and legal. Cloned hardware and legal software. To be fair these things are not great but they are so cheap that if you can play with it for no risk. I also consider most of these more of a decoder than LA. Even so they are good for programming purposes once your design is up and running.Free softwarehttp://sigrok.org/and grab a Saleae or Bee clone off ebay. You will need to match up with the list.http://sigrok.org/wiki/Supported_hardware#Logic_analyzersexample on ebay 8chhttp://www.ebay.ca/itm/USB-Logic-Analyzer-Device-Set-USB-Cable-24MHz-8CH-24MHz-for-ARM-FPGA-/271693865343?pt=LH_DefaultDomain_2&hash=item3f4237617f

author: arekm
author_rank: Unknown
timestamp: January 13, 2015, 08:52:50 am
content: 16 channel versions:http://www.banggood.com/USB-Logic16-100M-16-Channel-Logic-Analyzer-ARM-FPGA-Decoder-p-917243.htmlhttp://www.banggood.com/Logic16-USB-100M-Logic-Analyzer-ARM-FPGA-Decoder-With-18-Clips-p-91369.htmland some morehttp://www.banggood.com/buy/Logic-analyzer.htmlThe two above should work with sigrok, too.

author: pickle9000
author_rank: Super Contributor
timestamp: January 13, 2015, 06:27:40 pm
content: Quote from: Lightages on January 13, 2015, 06:43:47 amLooks like a real LA (has state mode). Small memory not great.When it comes to crappy factor of the Chinese knock-offs, I can't speak for all but I have given away a few after trying them out. The build quality is a pass (not great though). I know of one in particular that is used on the weekends, a couple years old and is still working. To be clear again these (under $30) are more of a protocol decoder as are the lower end Saleae. Good for programming but not getting your hardware up and running in the first place.

author: Mark_O
author_rank: Frequent Contributor
timestamp: January 14, 2015, 06:04:43 pm
content: Quote from: aviphysics on January 13, 2015, 02:43:51 amYes, if you need the extra performance, certainly.QuoteNo.QuoteThat's correct. Main disadvantage, loss of sync between analog and digital channels. If that's not a factor, not much point in looking at the MSO2000's.