EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: qwerty_face on May 23, 2010, 11:30:08 pm
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Hi all,
After Dave gave the thumbs up there on the USB Logic Analyzers, I was wondering if anybody knows of any fairly good value ones as I am in need of one!
Cheers.
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I've got the Salae one, for what I've used it for it seems pretty good. Though when you have an 8bit bus and control signals you wish you had more lines ;D
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Hi!
There's the pickit serial analyzer from Microchip. Don't confuse with pickit2.
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en028600
* I2C™ - Master
* I2C™ - Slave
* SPI - Master
* USART – Asynchronous
* USART – Synchronous
* LIN (external hardware required to meet electrical specifications)
* MICROWIRE
It features those interfaces, but it seems that it doesn't work on high speed buses. For example, SPI max speed is 1.25MHz according to the software setup. I am not sure of this.
This analyzer has everything on Microchip website, from the schematics to the pc software, so you can build your own analyzer if you want to save some cash.
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This one seem pretty nice to hack:
http://hackedgadgets.com/2010/03/29/zeroplus-logic-cube-hacked/
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I have the Intronix LogicPort LA. (http://www.pctestinstruments.com/). I really like it. It can solve those nasty timing issues.
The software is good and is easy to use.
Capture memory is on the low side, but with run length compression and good triggerring options, this hasn't been a problem for me.
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My $0.02 based on the research I did a little under a year ago:
- Saleae logic (http://www.saleae.com/logic/). A basic 8-channel/24MS/s USB logic analyzer that streams the data directly to your computer, triggering and all that stuff is done on your computer. Price is $150 or so. This gives you almost unlimited sample depth, but does limit the sample rate, and the highest sampling rates don't work if the USB bus is busy. The software will be ported to Mac/Linux at some point, but that's been in progress for like a year, so don't hold your breath. Pretty nice and intuitive software.
- Usbee SX (http://www.usbee.com/sx.html). Basically a clone of the Saleae logic, similar specs and price. Has a few extra features like the ability to output signals (these are all software features, the Saleae logic is supposed to have these features too at some point). The software used to be much worse, but to compete with Saleae, they released an improved version which is said to be much better than the previous software.
- Openbench Logic Sniffer (http://dangerousprototypes.com/2010/02/25/prototype-open-logic-sniffer-logic-analyzer-2/). This is an open-hardware/source logic analyzer, 70MS/s, 32-channels (16 are 5V tolerant), 2k-8k or so samples (depending on the number of channels in use, with RLE). Really low price ($50), software (SUMP) is not great, and there are currently a few problems. A revision with more RAM is planned in the future. If they get the kinks worked out and get the software into shape (or if Sigrok takes off), this might be the best bang-for-buck by far.
- Intronix LogicPort (http://www.pctestinstruments.com/). This one has by far the best specs and is the most professional, but the price is also much higher (almost $400). 34 channels, 500MS/s, 2k samples (with RLE), advanced trigger options.
- Zeroplus logic analyzers (http://www.zeroplus.com.tw/logic-analyzer_en/). The LAP-C-16032 (about $150) has pretty good specs: 32 channels, 100MS/s, 32k samples with RLE. The disadvantage is the horrible software (not very user friendly), useless triggering (only one level, they make a separate trigger unit to alleviate this), and the fact that they sell the protocols for big bucks ($150 for two!). I dislike companies that charge me extra to fully use the hardware I bought from them, and it doesn't motivate them to open up the software and let you write custom protocols. The upside is that there is a hack to upgrade them to more channels/RAM, but it's not as easy as the Rigol hack (involves actual soldering), and I'm not sure if it still works on the current version.
Since software is quite important for a USB logic analyzer, it's your only interface, I would make sure to try it (they all have demo versions that you can run without the hardware) before buying anything. My picks would be the LogicPort (if you have the money), Saleae Logic/Usbee SX (not much to choose between those two, the promise of cross-platform software sealed the deal for me), or the Openbench Logic Analyzer (if you want it cheap, can tolerate the software and don't mind waiting until the get it working properly). Eight channels if often enough for me with today's micro's (no external memory bus) and serial buses, but more never hurts. Even something like a 4-bit HD44780 LCD display will take up almost all eight channels. 24MS/s is tolerable with 8-bit micro's (buses up to 4MHz or so), but more never hurts. Sample depth can be an issue, run-length encoding helps, but something like an SPI clock will quickly fill your memory, but the better the triggering, the less you need a deep memory.
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We have the Intronix Logicport at work and it is a very useful tool especially for debugging embedded serial protocols.
It can decode SPI, CAN, I2C, RS232 and possibly more.
It can do this across multiple inputs, which can be defined as you like.
I find the CAN decode is especially handy as it handles the bit stuffing which makes the actual line signalling vary depending upon content.
It is not so good as a state analyser if you want to capture every sequential serial word and post analyse.
If you are happy with only timing analysis it is a damn good buy - compact and no noisy fans, unlike the old HP that I still use at times when I really need a state analyser, or more powerful triggering such as "if - then" sequenced triggering.
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I have a HP 1600B that i got off ebay cheap, Intronix LogicPort, Sump LA on the digilient spartan 3a and the gadget factory version.
I typically only use the logicport unless i'm doing a larger capture, the software works well and its really easy to setup decoders, i use it for can bus and memory sniffing. As said before the buffers a bit small but its great. The crimped wires on the connector are a bit thin and tend to wear out fairly quickly i've noticed, but are cheap and easy to replace.
The sump is a pretty close second, simply just because the software isn't as good, but it has a much larger buffer size. The gadget factory one is the cheapest but has the least features. I have the omla32 add on board to make it 5V tolerant.
http://www.sump.org/projects/analyzer/
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Thanks all, my budget is 100GBP which is like 144USD given current exchange rate. Gonna have to ponder on this for a bit.