USB logic analizer any good? - Page 1
Forum section: electronics / general

author: FreeThinker
author_rank: Frequent Contributor
timestamp: January 23, 2011, 08:54:13 pm
content: Any one used one of these?http://www.ikalogic.com/scanalogic2/Ok not Topend spec but seems usefull for debugging serial protocols I2C etc.£50 uk built, kit for around £40 or just the mcu and pcb.

author: RayJones
author_rank: Frequent Contributor
timestamp: January 23, 2011, 09:03:16 pm
content: Hmmm, 20MHz sample rate - I've found that can be too slow for reliable capture and decode of serial data streams that are up around 1MHz.We use the legendary LogicPort, been around for years, and it can sample up to 500MHz.If we sample 500kHz CAN stream at 20MHz, it is not always decoded reliably. :-(Bump it up to 200MHz and it runs sweet.Likewise sniffing SPI bus etc.I suppose you do get what you pay for.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: January 23, 2011, 09:21:52 pm
content: I think it samples and then you down load and decode so that may help? Also is it not possible to slow things down for debugging and once running ok run at full speed for testing? Won't pick up timing errors but should prove everything else is ok or am I making nubie errors in the way these (protocols) work, not very clued up with these yet.

author: RayJones
author_rank: Frequent Contributor
timestamp: January 23, 2011, 09:37:13 pm
content: Typically all these USB devices sample, download, decode.Slowing down the bus may be useful for confirming you clock / data phasing is correct on things like SPI, but a CAN bus is typically designed for one speed due to the multihost nature and the lack of a synchronous clock.Also it is typically the vagaries of running at full speed where the real issues lie, so debugging is best done at the speed that the system should operate at.If you can go even higher and it is reliable - ie measured setup and hold times are OK, you will have a very robust end design at the designed speed.So ultimately a proper DSO cannot be beat for checking for dodgy clock / data timings.Only once you know they are fine should you bother with the higher level decoding of what is happening on the serial bus.

author: tyblu
author_rank: Frequent Contributor
timestamp: January 23, 2011, 09:47:07 pm
content: http://www.seeedstudio.com/depot/preorder-open-workbench-logic-sniffer-p-612.html?cPath=75I have one. Haven't used it much but it supports up to 32 channels at 100MS/s, 16 at 200MS/s, and has 216K block ram (8x24K, 16x12K, 32x6k). It's cheap, and is made to support the open source SUMP package:http://www.sump.org/projects/analyzer/.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: January 23, 2011, 10:19:59 pm
content: So reading between the lines I get the feeling it's more usefull as a hacking tool on an unknown DUT than as a design tool?

author: RayJones
author_rank: Frequent Contributor
timestamp: January 23, 2011, 10:27:31 pm
content: No, not at all. It can be a very valuable design assist tool, but you must ensure you have quality signals to start with.However if the test device however introduces uncertainty in its measurements by not decoding the stream properly, then it is not trustworthy to debug your development with.As stated earlier, from my experience, 20MHz may unfortunately cause this to happen

author: Scrts
author_rank: Frequent Contributor
timestamp: January 24, 2011, 02:18:56 am
content: I have copied USBee AX PRO (Yes, that one which is new for >1000USD) + some modification, like buffer on input circuit. Works fine. We have Intronix LogicPort @ work which is really really GREAT!

author: veryevil
author_rank: Unknown
timestamp: January 24, 2011, 04:04:09 pm
content: Quote from: Scrts on January 24, 2011, 02:18:56 amAre you gonna release it or have you just copied it for yourself? Would love to see how inside one of them!

author: Chasm
author_rank: Regular Contributor
timestamp: January 24, 2011, 04:10:35 pm
content: If you can waive the analog input the inside is a CY7C68013A.Same for the Saleae Logic Analyzer.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: January 24, 2011, 04:37:38 pm
content: http://iteadstudio.com/store/index.php?main_page=product_info&cPath=2&products_id=221Worth a look

author: Scrts
author_rank: Frequent Contributor
timestamp: January 24, 2011, 05:00:47 pm
content: Quote from: veryevil on January 24, 2011, 04:04:09 pmIt's on my blog:http://www.socratesblog.eu/

author: Chasm
author_rank: Regular Contributor
timestamp: January 24, 2011, 05:27:33 pm
content: The iteadstudio version seems to have input buffers, but no ADC.

author: Scrts
author_rank: Frequent Contributor
timestamp: January 24, 2011, 05:53:29 pm
content: No point to have ADC there, because the simple USBee software can only capture the signal. PRO version can do it continuously, but You have to pay for it. Having a scope, which is able only to capture a signal once is useless.

author: Neganur
author_rank: Unknown
timestamp: January 24, 2011, 07:54:40 pm
content: I have a logic sniffer as well. It's fairly cheap for what it is capable of.Especially thealternative JAVA clientis nice.(The alternative Java client is developed and released under the General Public License, version 2.)

author: Scrts
author_rank: Frequent Contributor
timestamp: January 24, 2011, 08:19:40 pm
content: I would consider doing my own logic analyzer using FPGA if there would be a volunteer to program PC-side software using lets say QTI don't like that JAVA stuff...

author: tyblu
author_rank: Frequent Contributor
timestamp: January 25, 2011, 02:30:30 am
content: these guys wrote SUMP-- perhaps it could be ported

author: GeoffS
author_rank: Unknown
timestamp: January 25, 2011, 03:03:21 am
content: Quote from: tyblu on January 25, 2011, 02:30:30 amDon't understand the reference.

author: tyblu
author_rank: Frequent Contributor
timestamp: January 25, 2011, 06:06:11 am
content: Quote from: GeoffS on January 25, 2011, 03:03:21 amedited. no reference.