USB Logic Analyzer to go - Page 1
Forum section: electronics / testgear

author: MineBartekSA
author_rank: Newbie
timestamp: July 07, 2017, 06:26:06 pm
content: So let's go to the point i need a good and cheap USB Logic Analyzer that can (over USB 3.0) send continous readings or an USB Oscilloscope that can do the same thing. I need this to check some serial buses (like SPI, I2C or UART) on the go, or when i'm not able to get a proper oscilloscope. I'm looking for a device that will work (only slower) with USB 2.0 like with USB 3.0 because i only have computer with USB 3.0 back home and in my laptop i only have some USB's 2.0.I don't done much reschearch about those things but i looked for some USB Logic Analyzer's and i only find two of them. I know that's a loot of variables and i'm asking for a (i think so) expensive products but i think someone on forum full of smart people heard or know of something like this. BTW i want it cheap and on Logic analyzer 4 of inputs will be enough (but 8 will be awersome), but on oscilloscope 2 channels are ok (but i want 4 xD).I think i wrote evrything and i find something that is good enough.But still thanks for (at least) reading this.

author: colorado.rob
author_rank: Frequent Contributor
timestamp: July 07, 2017, 07:18:30 pm
content: QuoteDefine your terms. Cheap is relative.I own a Saleae logic analyzer and am very happy with it. It helped me diagnose some USB protocol issues I was encountering with a bootloader on an STM32 MCU. I'd recommend them to my friends. I also like that their software runs on a wide variety of platforms. Their USB3 LAs are not what I would call cheap, but if I needed to diagnose any high-speed protocols, that's what I'd buy.I really wish the Siglent MSOs would get USB FS protocol decoding.

author: MineBartekSA
author_rank: Newbie
timestamp: July 07, 2017, 07:36:14 pm
content: Quote from: colorado.rob on July 07, 2017, 07:18:30 pmSo the price in $, Euro you can multiplay by 4 and you can get the price that i have to pay in my country value (the great Polish zloty yey!).And the worse part is if the price will be in british pounds i have multiplay it by 5!That cheap. Around 1 000 PLN it will be ok. (it's still expensive and i don't think i will be spending that much money on it)

author: alm
author_rank: Super Contributor
timestamp: July 07, 2017, 08:05:48 pm
content: Sounds like theSaleaelogic 8 might be within budget. Not USB 3, but can go up to 100 MS/s in 4 channel mode. The only competition that I can think of are the clones which I will not support and only copied the old models (so no analog channels or other new features).Based on your requirements, you do not seem to need very high sampling rates. SPI will usually go up to a few MHz or so, so something like 12-24 MS/s might be sufficient.

author: AlexNorell
author_rank: Newbie
timestamp: July 07, 2017, 08:44:26 pm
content: What about the Open Bench Logic Sniffer for 16 channels, or the Bus Pirate for a few less?http://dangerousprototypes.com/docs/Open_Bench_Logic_SnifferThey are pretty old, and have a limited amount of capture length, but I've been using mine for the last couple of years without any issue.

author: TK
author_rank: Super Contributor
timestamp: July 07, 2017, 08:54:48 pm
content: USB 2.0 devices are supposed to work on USB 3.0 host.I like the Zeroplus LAP-C series. LAP-F is the new model with native USB 3.0 (works with USB 2.0 as well) but price is over $2K in the US

author: alm
author_rank: Super Contributor
timestamp: July 07, 2017, 09:10:39 pm
content: The original poster talks about continuous sampling. I believe that rules out many of the ones with internal memory. Not sure how hard that requirement is. Obviously it is a trade-off of almost unlimited memory depth vs sampling rate. For something like SPI or I2C, memory depth might be more useful than sampling rate.

author: AndyP
author_rank: Contributor
timestamp: July 07, 2017, 10:06:55 pm
content: The USB 3 options can be quite expensive, I've been using a DS Logic Pro, it's only USB2 but has 16MB of data and is fully open source, are friend recently bought one on ebay for ~£60.It will operate at:400Msps (4 bits)200Msps (8 bits)100Msps (16 bit)As has been pointed out above this is a still a buffered memory apporach, but it does have a 256MBit / 16x16M memory. At 4 bit, 10Msps this would allow 8 seconds of capture, in addion it has an RLE mode which extends this out far further!The design (and rtl) is open source for those really needing to tinker with the triggering and capture.http://dreamsourcelab.com/wiki/index.php?title=DSLogic_Core_BoardThis may be sufficient for your needs unless you need streaming over many 10s of seconds.Note some usb LA tools will struggle with logs that are too long.

author: alm
author_rank: Super Contributor
timestamp: July 07, 2017, 10:23:35 pm
content: Quote from: AndyP on July 07, 2017, 10:06:55 pmLike protocol decoding in the DSLogic software?That is something where the Saleae software is quite nice. Not saying it is perfect and there are definitely missing features, but it works quite smooth and snappy, even with large numbers of samples.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: July 07, 2017, 10:38:19 pm
content: There are a bunch of cheap Cypress CY7C68013A based devices on eBay (EZ-USB FX2LP)Cypress datasheetI do not know a lot about logic analyzers and you need to take a look at the datasheet to see if this might suit your needs. If it does: I lately ordered three of these from China and they are supported bySigrok. As far as I know the Salea logic is based on the same chip, but I did not try the Salea software yet.If you think that is something you could work with, drop me a PN with your address and I will send you one. I am quite surprised at how much more expensive things on ebay.pl are in comparison (4€ vs 12€). I sometimes order via ebay.com because of good exchange rates via Paypal - chinese sellers mostly offer free world wide shipping...Regards,Frederik

author: MineBartekSA
author_rank: Newbie
timestamp: July 08, 2017, 07:07:13 am
content: Quote from: frozenfrogz on July 07, 2017, 10:38:19 pmWhen i buy on ebay i ALWAYS buy on ebay.com because it's cheaper than ebay.pl and like you sayed chinese sellers mostly offer free shipping.I would like to have continous sampling to just plug in and see what's on the bus. But if this comes with a high price then i will be force to just try something else.

author: AndyP
author_rank: Contributor
timestamp: July 08, 2017, 08:49:21 am
content: Quote from: alm on July 07, 2017, 10:23:35 pmI prefer the DSLogic software to the Salea, I had great expectations for the Salea software but found Sale harder to:1: navigate long data,2: get easy measurements,3: jump to the next event4: get a clear i2c decode very basic.Given the popularity of Salae, I'm sure others will have a different preference, I use the tool that works for me.I have access to both, and generally use the DSLogic or serial Decode on a Micsig TO1104 scope (battery or mains powered).In day to day use we generally use the serial decode on the Micsg TO1104 scope, unless longer buffers are needed.

author: BFX
author_rank: Frequent Contributor
timestamp: July 08, 2017, 09:48:24 am
content: Look at this

author: tronde
author_rank: Frequent Contributor
timestamp: July 08, 2017, 07:24:52 pm
content: Quote from: frozenfrogz on July 07, 2017, 10:38:19 pmI have one of those, and it works at least on the slow I2C bus in sigrok. I have not tried anything else. I get a real time trace, but the decoding of I2C does not seem to be realtime.https://sigrok.org/wiki/Lcsoft_Mini_BoardI use the pinout of the module as shown here:http://forum.hobbycomponents.com/viewtopic.php?f=102&t=1891

author: mrm2007
author_rank: Contributor
timestamp: July 08, 2017, 07:48:54 pm
content: Hi,You can check these models @ seedstudio :https://www.seeedstudio.com/s/logic%20analyzer.htmlSent from my E2333 using Tapatalk

author: cdev
author_rank: Super Contributor
timestamp: July 08, 2017, 08:09:43 pm
content: I paid around $18 for my EZ-USB FX2LP LA, and its used a lot. For the money its been a value thats hard to match.

author: AndyP
author_rank: Contributor
timestamp: July 08, 2017, 08:24:20 pm
content: Out if interest what sample rate is needed.The dslogic will stream continuously (up to 1G sample) over USB 2 at a sample rate of 10MB/s or lower. So upwards of 100s, longer at lower sample rates.Or is the test for hours, and going generate 100s of GB of data. I guess you'll need one that does rle and time stamps over USB 2 to get date size down