Beginner Logic Analyzer - Page 1
Forum section: electronics / testgear

author: Minifig666
author_rank: Contributor
timestamp: December 29, 2013, 12:16:07 am
content: Hey all,I'm in the market for a logic analyzer at the moment, and I'm looking for some advice. I know a standalone logic analyzer is probably crazy overkill for a hobbyist, but stuff it, I want one!My specific reason for wanting one is that I'm developing a 7400 series CPU, so I figure it'll be more useful than my crappy "20MHz" scope.The Saleae USB thingies are tempting, but for the price I could have a fancy standalone piece of kit that looks cooler and is better for me.My budget is somewhat limiting, so I've tralled the net and found a few runners up:The HP 1650A with 1K sample depth, with state and timing analysis splitable in groups of 16 over 80 channels. 100MHz timing 25MHz state. ~£150The Philips Fluke (Ooh Fluke!) PM3585 with 2K sample depth, with state and timing on all 96 channels. 200MHz timing, 50MHz state. Includes one set of probes. ~£200The HP 1651B with 1K sample depth, 100MHz timing, 35MHz state. 32 channels. ~£150Finally, the Saleae with 1T sample memory, 12.5MHz sampling on 16 channels, and all the fancy up-to-date protocool decoding. ~£120I'm a little lost with some of the features of each unit, especially the different frequencies and the applications of the timing and state functions. If someone could give a little insight into what you would use each mode for that'd be much appreciated.Any suggestions as to which of the above would be best for a hobby shop, or if you have any other listings available in the UK that you think would be even better.Thanks very much in advance,Mini

author: Dave
author_rank: Super Contributor
timestamp: December 29, 2013, 12:24:18 am
content: You could just buy one of those cheapSaleae clones. Dirt cheap, probably works just as well as the original.

author: Minifig666
author_rank: Contributor
timestamp: December 29, 2013, 12:52:38 am
content: Hmm, as convincing as the "Saleae" sticker on the top is, I'm somewhat skeptical about support for seleae's software. That's the main things that put me off USB stuff is the software quality...

author: Dave
author_rank: Super Contributor
timestamp: December 29, 2013, 01:08:51 am
content: I have one of these cheap sh!t clones and it works perfectly with Saleae software.

author: Hypernova
author_rank: Unknown
timestamp: December 29, 2013, 01:10:37 am
content: Get the Saleae, for a beginner you need to sample for a long time to get a feel for what you are looking for. If you happen to probe UARTs the 1~2KSmpl memory is very limiting.

author: Minifig666
author_rank: Contributor
timestamp: December 29, 2013, 01:26:59 am
content: Ah cool. For such a low price I'll give one of the clones a shot, shame nobody's cloned the 16 really, but meh. Prehaps I can set up a load of PCs each with their own clone!Thanks, Mini

author: amyk
author_rank: Super Contributor
timestamp: December 29, 2013, 09:52:44 am
content: A lot of them go under the name "FX2LP development board" or similar, presumably to avoid arousing Saleae (but the hardware is basically the same - it's a single USB MCU with its GPIOs broken out). Those bare board ones you can get 16 channels out of if you use Sigrok software since the Saleae-8 and closed-case clones don't have the extra GPIOs accessible.

author: nctnico
author_rank: Super Contributor
timestamp: December 29, 2013, 04:52:29 pm
content: Maybe look for an HP/Agilent 16000 series because they have lots of channels. For developing circuits out of massive amounts of logic chips you may want lots of channels.

author: PlainName
author_rank: Super Contributor
timestamp: December 29, 2013, 08:15:51 pm
content: Quote from: Minifig666 on December 29, 2013, 12:16:07 amDepends entirely what you're doing. If it involves serial protocols then the Saleae wins hands down because it's the only one that does 'em out of the box. I have one and use it in preference to the HPs (I have the 1650A and 16700A), but that's mostly because it takes up practically no space on my desk whereas the HP needs a separate desk.On the other hand, if you're doing old world logic then the HP is great. Sure, it has limited (for nowadays) trace depth, but it records edges so the actual depth can be 1k events rather than 1k clock times. Further, the triggering is another world to the Saleae, which only provides simple edge/state like on a basic scope, so you don't have to capture an afternoons worth of samples in order to be sure you got the one event you're looking for.The last job I used the 16700 for was to debug a PCI bus. There are a ton of fast signals in that, and it was reasonably simple to write a state decoder so the HP would display the appropriate state details (memory read, config write, etc). Kind of like the Saleae I2C decoding but for 64 pins in parallel instead of 2. If you need to do that sort of thing (and this would include old world CPU/RAM/ROM/IO stuff) then there is no substitute to kit like the HPs. But nowadays everything is on-chip so there is nowhere to hook any of your 96 grabbers except on the 3 or 4 I2C/SPI pins, and for those the Saleae is far better.

author: Minifig666
author_rank: Contributor
timestamp: December 30, 2013, 12:27:47 am
content: So many options!I think for now I'll stick to a Saleae clone and see if I can get the thing up and running. Perhaps once I get a car sorted I can save some cash on postage too!Thanks for your help guys.-Mini

author: don.r
author_rank: Frequent Contributor
timestamp: December 30, 2013, 02:31:37 am
content: Quote from: Minifig666 on December 30, 2013, 12:27:47 amThe FX2 boards are like $9 delivered on fleaBay. You just need some cables and grips and your good to go.

author: Mark_O
author_rank: Frequent Contributor
timestamp: December 31, 2013, 02:18:05 am
content: Quote from: dunkemhigh on December 29, 2013, 08:15:51 pmThis isn't even close to true.Two examples off the top of my head are the USBee analyzers (with vastly superior software to the Saleae), and the ZeroPlus LAP series (like their LogicCube). Both have very extensive protocol handling capabilities, and the USBee even lets you easily define your own handlers. (Also possible on Z+, but a fair bit more difficult.)

author: Minifig666
author_rank: Contributor
timestamp: December 31, 2013, 02:24:27 am
content: I think he's referring to those I listed.The USBee things look interesting, but have a very substantial price tag.

author: Mark_O
author_rank: Frequent Contributor
timestamp: December 31, 2013, 03:02:56 am
content: Quote from: Minifig666 on December 31, 2013, 02:24:27 amI agree that some of the USBee'sareridiculously expensive (IMO), but others, not so much. TheirSX modelis only $169 USD. I assume that's within your budget.If not, the ZeroPlus is a bit cheaper. Perhaps ~$130 USD. A quick find on the bay (not a recommendation) ishere.ADDED: I went back and checked where I got my ZeroPlus, and it wasNKC Electronics. Icanrecommend them, and they have them on sale for $119, with free shipping (in the US). They include 52 free protocols, which should be enough to get you started.Since you've given no clue where you're located, I can't tell if that does you any good or not. (Well, I see you did give a clue, by mentioning prices in £, so perhaps US sources aren't overly appropriate. Other than to set some pricing expectations.)

author: abyrvalg
author_rank: Frequent Contributor
timestamp: December 31, 2013, 09:01:08 am
content: Btw, there are USBee SX/AX/DX clones too (even dual mode clones that can work as Saleae or as USBee)

author: PlainName
author_rank: Super Contributor
timestamp: December 31, 2013, 12:04:12 pm
content: Quote from: Mark_O on December 31, 2013, 02:18:05 amIt is for the selection in the root post. I could have mentioned a zillion and one other things (you made a good start!) but there would be no point because he asked about the specific things he was thinking of buying.

author: amyk
author_rank: Super Contributor
timestamp: December 31, 2013, 12:33:35 pm
content: Quote from: abyrvalg on December 31, 2013, 09:01:08 am5-in-1also exists, which adds FPGA/CPLD programming functionality. I don't doubt even more crazy combos exist.

author: arekm
author_rank: Unknown
timestamp: January 01, 2014, 08:13:58 pm
content: Also all (or almost all) these Saleae clones work with free logic analyzer software -http://sigrok.org/(since using original saleae software with clone hw is not allowed due to license issues).

author: uboot
author_rank: Contributor
timestamp: January 02, 2014, 11:42:40 am
content: I got this 50$-one:http://dangerousprototypes.com/docs/Open_Bench_Logic_Snifferhttp://www.seeedstudio.com/depot/preorder-open-workbench-logic-sniffer-p-612.html?cPath=75Works like a charm, 16 channels + 16 additional ones, up to 200MSa/s capture rate, up to 24k/channel (256K total) which is greatly improved by RLE compression, advanced triggering, open source hard & software, compatible with SUMP and SIGROK.Protocol decoding: 1-Wire, Asm45 bus, DMX512, I2C, JTAG, Line decoder, SPI, State analyzer, UART ....with this client:http://ols.lxtreme.nl/

author: AReResearch
author_rank: Newbie
timestamp: January 02, 2014, 11:57:42 am
content: I have an original Saleae logic. What sometimes worries me is that the input protection only goes to +/- 15V. So working on an rs232 interface is risky without additional protection.Apart from that it works great for me.

author: uboot
author_rank: Contributor
timestamp: January 02, 2014, 02:04:08 pm
content: The Analog Discovery - which I also have and greatly enjoy - has +-20V overvoltage support on its 3.3V logic inputs. But 16k per channel without compression is not much and bandwidth is limited by 12.2pF input capacitance.http://www.digilentinc.com/Products/Detail.cfm?Prod=ANALOG-DISCOVERY