EEVblog #436 - Saleae USB Logic Analyser Review & Teardown

hi its product review time well it was going to be mailbag time actually cuz I've had this one sitting in the mailbag for quite some time as you may have seen its from say Lee logic ah it's their 8th channel logic analyzer and well I know a lot of people want to see this thing so I thought rather than just slipping into a mailbag I'll do a full review so let's crack the thing open see what it is hundred and fifty dollar eight channel logic analyzer very affordable and by all accounts it's got a fairly good reputation so let's see if it's any good and here's the case and whew isn't a bit wanky you nice embossing there they've spent a little bit on the case there well you know to spend much to get that these days from China do you but anyway look at this lovely nice little ah don't think it's Pat it but it's one of those hard shell cases really quite neat zipper cases let's camera there let's whip this thing open and jeez where is it standing there it's tiny look at the size of the thing unbelievably tiny we've got a little care package of connectors here little micro grabbers as you'd expect there's a little point one inch head of cable and a USB cable and that's it no CD no software ah doesn't matter download it save a disk and check it out it really is tiny about 43 millimeters square and not very thick at all you could fit that in your fog pocket not a problem whatsoever I've been well you'd have to curl up the probes and you know they'd be a bit pointy but gee I don't know it's a nice little rugged machined aluminium and black anodized case very nice you could probably run over that thing in your car I'm trying to give that a bit of a twist on there but jeez that's pretty rugged I don't think surviving is going to be a ruggedness is going to be an issue for this thing so um there's a little mini B connector why are you using mini be what don't they go microUSB yeah I don't know anyway um look they've got that machined into their pin one on the standard point one inch header connector interface and the ground over there so you've got eight channels plus ground count the pins it should be nine and I see four screws on there hmm you know we say here on the eevblog don't turn it on take it apart yeah this has got a little t5 Torx screws on there I'm assuming that it goes into a little machined and tapped metal post in there that's what I'm assuming and I don't expect a lot of logic in this in fact I'd be surprised if it's more than like three chips probably one for the USB micro for the USB interface maybe a little logic device for the input buffer I'm not sure how much buffering this thing actually does and maybe the and the input buffer chip and maybe that is all she wrote it wouldn't surprise me if it's even less than that so it's crack this thing open are we've been mooned there we go there's the back arse of the board and that should just pop out yeah look at that one chip plus a couple of miscellaneous and a rig and there's the case machined aluminium as I said anodized and the top is actually our plastic it's um you know there it is it bends it's not metal at all but that's not a problem you still could run over this thing in the car and the board would be fully protected and of course yes our threaded inserts they're nice and of course this thing is absolutely bare-bones as far as a logic analyzer it's concerned we're just got the single op microcontroller here which we'll take a look at the eight inputs which go straight in through five hundred and ten ohms series resistors here we've got some input do clamping they'd be a low capacitive input do clamps so there is some input protection there for overloads and stuff like that but basically there is no input buffer chip or no input chips so it goes directly into the micro controller and of course it's got no effectively no sample memory in it it samples in real-time on the PC so it's effectively got an infinite sample memory and the sample rate just depends on the latency of your USB port um this is they claim the maximum is our 24 Meg samples per second on this thing but you've got to have a very low latency USB port to get that full transfering well you know that is adequate for most uses you know SPI I squared C another sort of you know serial interface stuff but you know this is not a serious you know professional in logic analyzer not by any means and by virtue of the lack of then input latch there this thing is effectively our timing analysis only it doesn't do state analysis mode unless one of these are pins here can be used as an external clock input and it can actually latch the data inside I doubt it so you've got timing analysis only but once again for 150 bucks general purpose you know low-end logic analyzer yeah that's all you need and I don't see any pull ups as well there could be some internal to the chip just those dodgy internal pull ups on the chip but they also claim that as far as crosstalk on the channels goes if you leave an input channel floating then it may actually pick up crosstalk from the other switching driven Channel so that's a bit of a worry but uh you know in the end it it doesn't matter because if you know you're not using channels 4 5 & 6 you just switch them off in software and the input logic thresholds on this thing are of course are fixed because there's no external circuitry to set your logic threshold so in this case um it's only got one set of our fixed logic thresholds there 16 channel version by the way has that two sets of logic thresholds this one is fixed with a logic low of naught point eight volts and a logic high of anything over 2 volts so of course that means it doesn't work on 1.8 volt systems and it may just by sheer luck but you know you wouldn't I count honor for any serious work so really it's only capable of being used on that 2 volt two-and-a-half fault three point three and five volt systems but of course that pretty much covers um you know every major system that you're going to work on I mean if you're working on 1.8 volt logic systems you know you're probably working on a pretty serious system and you probably need a more serious logic analyzer anyway and it looks like we have ourselves a low dropout 3.3 volt voltage regulator there there's those input diode clamps you can see them in standard six pin package there it's got D or 46 on I'm not going to bother looking up the tight that would be a low capacitive type you can see the input serious protection resistors that there so basically it goes directly from the input pins through series resistors through the diode Klan switch a diode clamp to the positive and negative rails you can do those with individual diodes but it's just cheaper and easier in most cases to use these little packages that's what they're designed for there are cheap and popular and of course that's duplicated over here on this side will go forwards this is another Dyer clamp we've got our 24 megahertz crystal oscillator we'll have a look at the microcontroller datasheet in a minute it's a cypress one but that's about all she wrote we've got ourselves a a poly fuse there excellent but well that's all you need and you can see we're up to a revision seven on the board they've gone through quite a few revs on this little beast this thing's been out for a couple of years by the way so I would have expect any kinks to be ironed out and curiously it looks like it's a your four layer board you can see that dark been in there the extra rot layer so um yeah they've gone to the effort to go for layer armed internal ground and power the microcontroller is a Cypress CY a 7c 6801 3a - 56 it's an 805 one let's go to the datasheet and here's the internal block diagram the one where god of course if he is the 56 pin SS o P as packaged as you saw and it's an 805 one core operating up to 48 megahertz and well yeah they're going to need that because it's for clocks per instruction cycles so you've got to wonder how are they getting that maximum sample rate of 24 megahertz when the 805 one call is only capable of 48 megahertz with that for clocks per cycle because if you're using your GPIO down here it you know I you just can't do it it's not possible but AHA look down here folks there's a separate four kilobyte FIFO with its own data input down here so clearly they must be using this FIFO and if we dig further in the datasheet which I haven't yet will almost certainly find that that FIFO is capable of first-in first-out buffer by the way so it does have buffering and that of course is what they must be using for those higher sample rates otherwise there's you know no way in hell that the program core running at that can read the GPIO and update the memory and do everything else at those sort of clock rates it'll probably only be a few megahertz tops or something like that so it's got to be using that FIFO and I think if we traced the board we'd probably find that those logic inputs go to the FIFO buffer and I just check further down in the datasheet and sure enough are the inputs go directly to port B which is the down on the bottom side of the pins down here and there actually are dual purpose pins they're GPI F general purpose i/o interface pins but they're also FIFO data pins are 0 through 7 as well so it's almost certain that they're using the FIFO in there but I also found out that the general-purpose some interface actually has a selectable interface clock of up to 48 megahertz awesome so I'd have to read further into the datasheet whether or not they actually use the GPI F and there's some sort of a shortcut down in the FIFO although it doesn't show it in this block diagram it shows that it has to go through the address common address data bus into the RAM there so whether or not that can actually sample through the GPI F into there at 48 megahertz rate independent of the frequency over here yeah I don't know but it's most likely that they're right using the 4k our FIFO there to buffer that data I know I would so one thing I'm curious to know and I'm not sure if I'm actually going to be able to check this or whether or not it's obvious in the software but is there any thing in the software that tells you that the latency is too high on your USB port and it's not able to get that data out at that clock rate is it smart enough to know that oops over you know I've missed some data you know we've got a buffer overrun and there you know all hell's breaking loose and well it's not working at that maximum speed because the last thing you want is data corruption or data dropping out through one of these our USB you know when effectively a real-time USB interface with just a little buffer in between to buffer the data because if you've got another USB device sort of you know hogging the port or something like that then you know you don't want your data to our drop out and your software not to know because that would be a cardinal sin you don't want that to happen which is of course the advantage of a proper logic analyzer like a real logic analyzer with its own internal sample buffer memory but of course that's a higher end higher price and it's got some limitations because well it's a limited buffer size you can do buffer data compression and a real-time data compression into memory and stuff like that on some of the higher-end logic analyzers even the low E and some of the USB ones do that as well in a similar sort of price range but this one of course has the advantage of unlimited memory assuming that you stick within that data throughput rate now of course with the cables here they have actually color-coded them of course and you might think well black goes to ground over here but no it doesn't Blackie's follows the color code channel zero you note one two three four blah blah blah and they've actually labeled the ground lead there the gray one so that's how you're supposed to put it not the other way around it would have been nice if they labeled these ones as well with the channel numbers and of course we got standard fare here on the little mini grabbers like out there you know par for the course you can buy them anywhere at Diamond doesn't if you lose them standard dual sided pin like that and you can just whack them in either side and go and probe and by the way one of the good things about these is that you can plug them directly into nought point one inch headers like that so by all means if you've got room on your board and you know you're going to want to have to probe the thing it's a common practice just to build some point one inch headers add them to your board layout just going to various single signals you need to probe and then you don't have to dick around with the mini grabbers like this you know and they you know they fall off if you bump them and you know err fiddly to try and get onto various pins directly on your chip much nicer if you use a point one-inch header and you'll lot find that are fairly common in a lot of commercial designs but so but all means do it up make sure you add a ground point as well and it can be useful to work on some power in there for some external circuitry as well just in case just a little tip wah-wah is just pushing the ground thing in here and it just pushed this apart like this so yeah folks these aren't the best quality mini grabbers bummer but they do work but of course that's not broken it just slips back on there not a problem I know what you're thinking you don't get much hardware for your hundred and fifty bucks do you well of course not because with a logic analyzer one of these USB logic analyzers it's all about the software folks and that's what you're paying for paying for good software so let's put this thing back together hook it up try it out alright we're on the website and let's download it and look it's got everything it's got XP Vista and Windows 7 32 bit and Vista and 7 64 bit support it's got Mac OS s OS X if you're into that sort of thing leopard leopard + tiger I don't know I'm not a Mac person and it also supports Linux as well for you penguin fans out there 32-bit and 64-bit let's download it I'm going to use the windows 7 version and I won't bore you too much with the details of the installation but let's see if it works and is it quick I don't know status bar nothing come on and it asks you to install their serial bus controller as well it looks like they got their own nut driver for this thing so yep not a problem I'm not going to always trust them hmm launch the software we're done folks and bingo oh we're in too easy look at that and of course if we have a look up here it's disconnected because we haven't plugged it in yet so presumably let me try that do it and install in device driver software at logic device was found but there was a problem connecting to it another application may be using it ah looks like I've got to shut it down oops well that was absolutely no dramas whatsoever it just died in store didn't even tell me in the background and bang it's a West Radian and there it is up the top connected looks and there's options menu over here which you can't see them all maybe if I can I can't drag my capture window but yeah we've got preferences displaying ASCII art there we go they pop up over here so save screenshots say screen region display in ASCII binary decimal hexadecimal users guide and give feedback and report issues this is the latest version let's have a look at the Preferences pre trigger buffer size okay excellent that's what you want you want some pre trigger data as well ten me examples only 10 million samples folks if you used to our logic analyzers with building memory then well 10 million is an absolute luxury enable longer captures up to one terrorist samples before geez that alert depend on data compression I guess as well because it would I prefer it would do some data compression before it writes it to disk and check for updates animate zoning and zoom in view state after new CAPTCHA what are we got here enable single click zoom aesthetics Oh use arrow glass tile yes no there we go ah look at that that looks bit better ya didn't what the other one was a bit wanky so just when you thought this thing didn't have many options and preferences and you know you're probably asking where do you set up all your serial data spi well you just noticed this analyzer down here look at this plus here it is CANbus dmx512 brilliant you don't get that very often I squared C I - SVU audio freaks out there PCM stuff the i2s audio standard Manchester one wire our bus for you people working on one wire you know maximum Dallas one wire and other one wire stuff async serial simple parallel SPI uni i/o all your basics are covered there with a few bonus extras although there is one that's missing there and that's a JTAG of course but JTAG usually quite high-speed might have been out of the realm of something like this but it I guess it would have been nice to have JTAG in there because a lot of logic analyzers will actually you know won't have JTAG even high-end ones won't have a JTAG option and as far as measurements go we've got width period duty cycle frequencies show the bytes show timing markers and show errors as well well only one thing left to do feed some data into this sucker and see what it does now of course I always like to try and use these things without reading the manual at all because that's a true test of you know is this thing user friendly or not know if you can familiar with logic analyzers in general or some other bit of teske turn it on can I use it is it intuitive well up here we've got one and we've got our number of samples here we've got our sample rate and start and I've hooked up an I squared C bus to it and I can just hit start here and occasionally I'll get blank data because it is that packet based there we go I get it a few times blank data and then occasionally I will capture the data that's because I'm no trigger is that setup at all and that's the first thing I notice what where's the trigger capability on this thing like how can i you know trigger on a data packet or something like that and you know we've got some analyzers down here let's go I squared C analyzed the settings we can not set it up there we go it's audit it looks like it has it automatically detected no of course the clock is channel 0 up there so we need to set that and data is channel 1 so it hasn't automatically detected that address display 8-bit read/write I think I'm doing 8-bit read/write so let's save that and it automatically labels them nice that's another thing I was going to check rename them yep beautiful SEL SDA there it is all nice there we go and it's put the decoded data in there beautiful ad look at that it's got the acknowledge in there and everything else nice I like it off to a good start but dumb I still don't know where the trigger is because we're just reading random data there and we'd find it if we sampling hello come on where's my data there we go it eventually got a packet and just scrolling around the data here if I use the mouse wheel to scroll in and out then that is zooms and expands the data that's exactly what I'd expect excellent and then left button oh I just hold it down and it automatically sort of you know drags it looks like it's got some sort of you know some sort of a buffering action on that pain stuff but I just grabbed the left button and drag that left and right and that sort of work so let's go out like that and there you go you can see my multiple data packets there and there it is we actually need more samples than that this is where the huge number of samples comes in as an advantage folks let's go up to 10 Meg samples for example takes a while but look at all those packets we can capture brilliant now usually to get that you either need a logic analyzer with a 10 Meg sample buffer or and or one with that data compression that actually compresses the data real time so that it doesn't during all these are dead periods a one of those logic analyzers with data compression won't waste up you millions of samples is story in just all one there it'll go one during that time period and only needs to store a couple of bytes so that's the advantage of those ones that data compression this one because it's real-time USB it doesn't need any of that data compression it doesn't store it on the device itself but as you can see we've captured a whole bunch of I squared C packets nice and if we have a look down here we can actually open up new tabs as well as going to existing ones it looks like it's got the ninth tab there and then we can copy various our stuff to the capture tab not sure what that's doing but it looks pretty flexible one thing I just noticed in that it these data labels here haven't copied over to these tabs over here now I'm not sure if that's a you know and you can change the label on that too by the looks of it I'm not sure if that's a feature for some reason or whether or not it's a small bug it looks like I found the trigger here there's actually for this by the way for the channel here they've actually got you can show and hide the various channels you can move them up and down as well you can't actually drag them which you know I would have expected to be able to grab that and just drag it around but yeah you can actually move it mentally I guess it's not too much of a drama you only have to do that once really when you're setting up your logic analyzer to you know to look and do exactly what you want but in terms of like we can reset trigger here but look we've only got requires a rising edge transition and requires a logic one to be present when rise in and that's basically um it it doesn't look like at the moment anyway I haven't found it that you can set up like a data packet trigger or anything like that mmm now one thing I really like are these are auto curses as you can see when I actually go in there you can see that little timing cursor change you can see the data look there's no data at the moment because I haven't actually move my cursor over something I don't even have to click on that and it shows me the width the period the frequency and the bite as well very very nice like that now I know it's grossly unfair to compare it to my Agilent infinite even mixed signal scope here but that's what I've got it doing I've got the scope actually generating one of these are training signals demo signals down here for the I squared C bus and of course it's got you know real-time decoding and hardware-based decoding as well so this you know this is a pretty good logic analyzer in that respect now as you can see there's actually some data changing inside this thing as well as a bit of that timing jitter as well going back and forth and that's obviously deliberate and you can see all the data packets in there and they do change like that in there in time period and we of course triggering off a reference to one packet here and of course that's what we're not doing at the moment with the Sayle logic unit we're just you know free triggering and just capturing whatever we get whereas you know we want to actually be able to set a trigger point like that I mean any good logic analyzer should be able to set a trigger point for the data so in effect if we set a trigger point and we can't see the data changing like for example we go in here you can see that the data is actually are counting up you know 2 4 6 8 2 4 0 or 20 40 60 80 stuff like that so if we can't capture that on the Sayle logic then well it's you know not nearly as useful as a real logic and a real hardware based logic analyzer like this one and of course the other thing I like is the decoding of the I squared C bus itself look at tells you exactly what's going on there it's a setting up a right to address 2 to 6 with an acknowledge and then the data byte is R 16 with acknowledge so you know it's a it's doing the business there I really like that but to actually check that this is accurate I'm assuming it is otherwise people would have reported issues and stuff like that if they were any they would have been fixed but for me to actually check that here I need to ensure that that packet I'm looking at is exactly the same packet that I'm getting on my edge illan scope and unless I can trigger on exactly the same packet I'd have to go through and look at every one of them well I did relent and read the user's guide it's not massive but it is well-written and well know folks I'm triggering is all you see they're just you know basic positive or negative edge triggering with data high or low and that's it um there's no ability to trigger off a packet in real time and that's rather disappointing I don't know whether or not that's a horsepower issue to do with the PC to be able to process that data in real time I wouldn't have thought so especially you know add the capability at some lower sample rates maybe you can't do it at 24 megahertz or something but gee I don't know pcs are pretty powerful these days I would have expected I'm so I'm quite disappointed that there is no trigger or not data and stuff like that or or trigger on an I squared C error for example so you can see that you know have it sitting there just sampling away sampling away so if you've got a data error on the bus you're trying to decode and well you know you want to just capture it and capture the data and just have it sitting there in the background in this data only occurs you know once every hour you want it just to sit there and wait for that trigger event you know look I got an error on my I squid C bus and boom it'll you know capture the thing but it really is a very bare-bones interface I do like it it's nice and the decoding is nice but in terms of triggering and data analysis and stuff like that it you know it just doesn't really compare so yeah I mean you're paying a bargain-basement price for a logic analyzer and you're getting quite usable software for the price but ya don't expect you know professional league triggering performance and stuff like that look I can't even look there's no way that I can even search like where's the search capability for actually finding this data right confirm restore if I go over to I squared C I can export the data save as text CBS that's great okay and but you know how can I find data let's say I want to find something where address you know to to to popped up and popped up or something how do I do that you can by the looks of it and by the looks of it I can't even like real-time update this display so let's say that I want to do you know trigger off the you know rising edge here and by the way I can't even trigger off like a time period like oh it's been high like I can't even say oh it's bit okay it's been high for you know X milliseconds or whatever and then trigger on the first point after that can't even do that you know we often call dark pulse with triggering it just doesn't have that capability but anyway I would like a you know I can I can capture the data single-shot capture but where's like the free running mode where I can just you know do that because then I'd be able to see if I was able to trigger off for example that pulse with ah why does that spring back that's really rather annoying now let's swings back as Adam at ik Elise wings back sometimes it does it sometimes it doesn't don't know what's going on there it could be a peb CAC error I don't know but yeah like if I was able to trigger off that first edge there after a time period then I'd be able to just sit there watching this data packet refresh refresh refresh but there doesn't seem to be a capability to do that auto are sampling an auto triggering bummer one good thing I like is it does seem to have fairly extensive art data export functions you can select which channels you want to export between specified art time so you don't have to export the whole lot a binary CSV and VCD I know what V CD is off the top of my head but there you go it has all these different formats and then you can that for the CSV stuff you can not do coma delimited tab-delimited all that sort of stuff really quite flexible I like it so if you want to analyze your data in another package looks like it's going to do the business and another good thing it looks like you can have multiple R buses and decoding on at the same time like I'm trying to set up a synchronous serial 1s a rs-232 one at the moment and of course it it still has the I squared C there and it automatically like if you go in here set it up if that tells you that these two are already in use by the I squared C so looks like you can do multiple ones well as you'd expect because really it's only just you know decoding this stuff in software after the fact so really it should be able to do anything if you can capture you know so really you could with eight channels you could capture out four separate SPI four separate I squared C buses or a synchronous serial buses at the same time beautiful but one annoying thing is I was on this tab here and I changed my labels and channels up here but that only applied to that tab so when I go back over here to this tab there they haven't changed ah I don't know is this a feature or not well I'm looking at my rs-232 signal here Rx and TX and it looks exactly like what I'm getting on my adilyn scope there it looks so faithful but it's telling me there's a framing errors in there so I've got this set to our auto board rate detection so maybe I maybe that's not working very well and I need to select a fixed baud rate let me try that hi it had detected that the auto baud rate was twenty thousand 833 it's actually nineteen two so let's say that and try again here we go start boom no it was still got framing errors now if we have a look at the data down here we can zoom out on the scope as well and you can see let's look at this low transmitted packet here and you can see that the data is completely faithful no problems at all there but of course the data is incorrect we're expecting our 23 hex here and our 31 hex and we're just not get in that so yeah it captures it fine but decoding not for some reason I don't know and I'm just doing a quick SPI bus and analysis and capture here and it seems to be working just fine matches the Agilent not a problem is just counting down I'm just doing the output line here I'm just capturing that there's our clock signal up the top there's OSPI enable and there's our data and this particular example I'm using is just counting down and sure enough it does count down it's not counting down by one by the way so that the data is correct so not a problem actually I think this tab based business I don't think that's a bug I think it's specifically set up so that you can specifically save and capture that particular data that you were working on at that time so that's why it doesn't auto change the labels and stuff when you go between them so yeah I take back what I said about that I think it's fine so the verdict on the sale II illogic eight USB a logic analyzer 150 US dollars or there abouts well it's pretty done basic as you saw um I was actually quite disappointed in the software and if you wanna check it out for yourself against download the software freely from the website of course and but it's very bare-bones um it's nice I like the way it operated but jeez you know there's no as you saw that I could find anyway I stand to be corrected no our serial data triggering the capability no free running mode it just well you know jeez I expected more this thing's been out for quite a few years actually so I expected them to keep adding features to the logic analyzer software but I don't know what was like a couple of years back when they first released it but it's pretty darn basic and I'm pretty disappointed I expect more from that so really for 150 bucks I don't know how it compares with the other USB logic analyzers out there haven't looked at them also I don't know you have to weigh that yourself but it's got to get a some thumbs sideways at best really I might don't mind it the harbour is nice and rugged the software seem to work quite well for what it did but very very basic and by the way the 16 channel version of this double the price the logic 16 you get faster speed on it 100 megahertz for two channels and then it drops four extra channels after that so there's some extra hardware in there to do that the software is the same so you pay that extra money and well is get very basic software it's okay for just you know general use really if you just want to muck around capture your SPI or I squid sea bus and stuff like that low speed stuff and it's okay value for 150 bucks but just wish they'd add more features anyway if you liked the review please give it a big thumbs up if you want to discuss it jump on over to the EEV blog forum catch you next time you you

Channel: EEVblog

Views: 198,417

Rating: 4.9070134 out of 5

Keywords: saleae logic analyser, logic analyser, logic analyzer, saleae logic analyzer, logic 8, 8 channel, 16 channel, review, logic analyser review, teardown, pcb, how to, tutorial, mailbag, eevblog, cypress, usb, usb logic analyser, software, driver, probes, i2c, spi bus, decoding, spi bus decoding, i2c bus, spi

Id: 7OCPWCdg2ys

Length: 37min 3sec (2223 seconds)

Published: Sat Mar 09 2013