entry level logic analyzer

[Mehran]

Hi guys, new to electronics . I come from a heating background(i am fix gas boilers in the UK).

what i am after is a way to look at and learn from spi and manchester code. my goal is is to build a modulating room stat basic around a HVAC com protocol (which is manchester coding).

I seen this
http://www.ebay.co.uk/itm/MDSO-LA-20MHz-USB-Digital-oscilloscope-48M-Sampling-16-channel-logic-analyzer-/251119761248?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a77e77760&_uhb=1

it hints at being able to be use with the saleae software. it also have a oscilloscope (I know its not a real oscilloscope but it could be useful).

am i wasting my money with this chinese knock off and go with a better make?

or not to bother at all?

[Psi]

Once you understand it manchester code is just as easy to read as non-manchester code. You just have to keep an eye on where the intermediate transitions are so you don't treat them as data.

But yeah, SPI is much easier to debug/view with a scope or logic analyzer that can decode it on the fly.

oh, and your link doesn't work.

[Mehran]

fixed the link

[logictom]

For an extra ~£30 I would go for the Saleae Logic, it is a good bit of kit and the software is very good.
I haven't used mine lately but if I ever ran into an issue their support answered emails within a couple of hours always sorting the issue, I don't think you'd get that sort of service with that chinese knock off.
I haven't had a go with a 'proper' logic analyser but wouldn't mind a go with the Agilent X series scopes with the built in analyser, looks like it would do the job nicely 

[Smokey]

Don't expect to use the analog channels for anything serious.  It's probably about on par with the Pocket DSO think Dave just reviewed.
And it looks like you need to know how to read Chinese to use the software.

I'd say... pass...

[kripton2035]

this is *almost* the same item...
http://dx.com/p/usb-oscilloscope-and-logic-analyzer-93518?item=1


this is *almost* the same item for the logic analyzer part
http://dx.com/p/logic-analyzer-w-dupont-lines-and-usb-cable-for-scm-black-148945?item=7


both of them are cheaper and enought for what you intend to do...

[Mehran]

that usbee ax pro is very cheap will it even work?


anyway thanks for the heads up

[arekm]

AFAIK Saleae Logic 8 channels is simply Cypress CY7C68013 and that's it (well, connectors, too).

http://mdiy.pl/uniwersalna-plytka-analizatora-logicznego/ if you want to make your own (in Polish, google translate should help).

http://hackaday.com/2011/12/15/saleae-logic-analyzer-knockoff-hacking/

But well, you won't get software that way.

[george graves]

Go with a Saleae unit - plus it comes with really nice leads.

[richcj10]

I have a Saleae logic analyzer. It is one of the most useful items I have.
Support is amazing. They really stand behind there product.
If you are on there beta team you get all the updates.
This includes all the different decoding formats it supports.

[cidcorp]

Ok I second the suggestion of the Saleae logic devices. 

I own the Logic 16 and would recommend it to anyone.  The software it uses is really well written. It supports
several protocol decoding: I2C, Async Serial, SPI, 1-Wire, CAN, I2S, PCM, UNI/O, Manchester and MP Mode.  This list
has grown a fair bit from when I was first interested in the Logic/Logic16.

Logic(8 channel)@$149USD or the Logic16(16 channel)@$299USD are both excellent choices.  The come with a no hassle warranty.
Plus Customer service is probably the best I've experienced in a tech company.  You would not be disappointed.

Now for the dark side, if you did want to choose a dirt cheap alternative, try googling:  "CY7C68013 logic"

i.e.: http://blog.lcdynamic.com/2011/02/logic-analyzer-cy7c68013a-core.html

There are several <30$ options out there using the Cypress Semiconductor CY7C68013 micro.  Apparently older versions of the
Logic software will work with the boards.  New revisions of the code detect clones by doing some form of latency check.
Although this option is cheap, you are in a way 'stealing' the logic software for free and the CY7 dev boards are mass produced on the
chinese markets.

All up to you, but I suggest the Saleae Logic (or 16), at least your supporting the developer for the awesome logic software they produce.

Also important to note the the Logic and CY7C68013 boards both lack input protection, and do not support several target voltages.

My 0.02, hope it's helpful.

Chris

[andyturk]

Saleae is great. I have the Logic16, seen here just above the breadboard on the right:



The software is really good too, and it runs natively on a Mac (as well as Windows and Linux):

[MrQuan]

Don't want to hijack this thread, but I'm in a very similar situation.

I'm fairly novice with electronics, but I'm starting to get more into microcontrollers and communications.  I've been looking at buying the Salaea Logic16. An EE at work told me any USB scope or logic analyser will end up junked, so I should just get a real desktop logic analyser and not a toy. He said that he often uses CMOS signals that are up to 15V, which would kill the Logic16 (max input of 6V).

I'll usually be using it at under 5V (SPI, I2C, TTL), but I do play around with RS-232 and RS-485 (up to 12V, and inverted lines). I imagine my DS1052E will help me here, but is there a good way to attenuate higher voltages? Or is the Logic16 essentially useless here.

Now, this is a hobby for me and I don't want to sink big dollars. Has anyone experienced issues with the USB performance or 6V max voltage? I'm thinking for $300 it's worth picking up... but now I feel like I should have got a DS1052D instead (scope with 16 logic inputs).

Any thoughts and ideas would be appreciated, many thanks.

[kripton2035]

the analog inputs of the rigol ds1052d accept some 400V
but I'm not sure the digital inputs accept even 12 volts ?
it's written nowhere on the commercial documentation
may be if someone has the user manual ?

EDIT : it accepts 40v on digital inputs so it's ok for your application

[Tasman]

I recommend the Intronix LogicPort:  http://www.pctestinstruments.com/  $389 plus postage.  It has 34 channels @500MHz sample rate, can handle +/-40V DC and 15V pk-pk pulses on inputs and lots of other good features.  I have owned and used one for a couple of years with no problems.

[DrGeoff]

I recommend the Intronix LogicPort:  http://www.pctestinstruments.com/  $389 plus postage.  It has 34 channels @500MHz sample rate, can handle +/-40V DC and 15V pk-pk pulses on inputs and lots of other good features.  I have owned and used one for a couple of years with no problems.

Agree. I've had one for a few years as well and find it very useful and good value for money.

[deephaven]

I recommend the Intronix LogicPort:  http://www.pctestinstruments.com/  $389 plus postage.  It has 34 channels @500MHz sample rate, can handle +/-40V DC and 15V pk-pk pulses on inputs and lots of other good features.  I have owned and used one for a couple of years with no problems.

Agree. I've had one for a few years as well and find it very useful and good value for money.

+1 here also

[nctnico]

I recommend the Intronix LogicPort:  http://www.pctestinstruments.com/  $389 plus postage.  It has 34 channels @500MHz sample rate, can handle +/-40V DC and 15V pk-pk pulses on inputs and lots of other good features.  I have owned and used one for a couple of years with no problems.

My experience with the Logicport is not so good. I have issues where the USB connection got lost which results in the program stopping without saving the setup. The 2kbit memory is also way too short and don't expect to do anything usefull with the 500MHz samplerate. You need real probes and a real logic analyser. Better go for the cheap Chinese logic analysers if you want good value for money.

[JoeyP]

I recommend the Intronix LogicPort:  http://www.pctestinstruments.com/  $389 plus postage.  It has 34 channels @500MHz sample rate, can handle +/-40V DC and 15V pk-pk pulses on inputs and lots of other good features.  I have owned and used one for a couple of years with no problems.

Agree. I've had one for a few years as well and find it very useful and good value for money.

+1 for me too. I've had a Logicport for years and use it often. We also have 2 of them at work. Though we have Agilent units around, we seem to always be competing for the much easier to use Logicports.

My experience with the Logicport is not so good. I have issues where the USB connection got lost which results in the program stopping without saving the setup.

I've never seen this happen. In fact, I find I can even disconnect the USB cable for a few seconds during live capture. When the cable is plugged back in, the software resumes capture as if nothing ever happened. Seems very robust to me. Quite a few Logicport users on this forum. Anyone else seen any issues?

The 2kbit memory is also way too short and don't expect to do anything usefull with the 500MHz samplerate. You need real probes and a real logic analyser. Better go for the cheap Chinese logic analysers if you want good value for money.

It's not 2kbit, it's 2k samples (apparently 68kbit). But that's a minimum, and I find the hardware sample compression to work well, often capturing traces that would be impossible for analyzers having even 1m or more samples (without compression). I've also found the 500MHz sampling to be quite useful for solving timing issues, though a higher sample rate would be nice.

If by "cheap Chinese logic analysers" you mean the Rigols, forget it. While the scopes may be decent, the analyzers are much less so. I know two people who own them. One describes the logic analyzer section as "just about useless".  The other one gave up using it altogether. I've also seen forum threads with dozens of posts by people seeing signal integrity issues with the Rigol logic analyzer pods.

[kg4arn]

Can anyone comment on the Agilent X-series Logic analyzer option versus the USB PC based products?

I have an Agilent DSO-X-3024A and I have been thinking about the upgrade to add the logic analyzer.

[free_electron]

there's different things at play

1) the salae , usbee and others are 'usb streamers'. they are ntohing more than a simple 8051 cpu that has its input fifo sample as hard as it can and they stream that to the PC. USB is, by design, unreliable in terms of throughput speed. It doesn't need to be deterministic in time. it is a stream pipe. if speed fluctuates , who cares as long as the sequence is not lost.

and this is the problem with using usb for realtime transport : the sampling speed may go up and down and your 'analyzer' will lose samples. the sb controller on your motherboard has a hub built in. So you do not know what channel is shared with what else ... plug a usb drive or mouse in the same root hub as the salae or usbee , jiggle the mouse or copy a file to usb stick and it all goes to snot....

The salae 16 solves this by having an on board buffer memory that can overcome part of this problem but there are still situation where it will fall over

2) A better usb based analyzer will have an on board trace buffer and does not rely on the usb transfer speed. Machines like this are the logicport and Chronovu. they solve this problem , but if you run out of memory you run out. done

3) none of the above (1 and 2) are real logic analyzers due to the fact that they neither offer timing (so called timing mode)  nor step synchronisation (so called state-mode). They cannot trap glitches inbetween samples and they cannot listen to an external clock. they have their own internal sample clock and they only look at the points in time given by that particular clock. They are blind inbetween, so you cannot check setup and hold time violations for example and they cannot be driven by a master clock to run in-sync with a system to be debugged. They simply lack the necessary hardware to do this.

Furthermore they cannot do things like sequence triggering nor can they run state logic tat tracks execution and fires the capturing of the abnormal condition.

So do not be misled !

The standalone units are often slow as well. 100 Megasamples and they fall over... simply because designing fast logic requires a different aproach.

the built in logic channels in an MSO are far more capable than these usb boxes. but they still are no match for a real analyzer like a 16900 series ...

That being said : the USB machines are perfect for tracing some serial protocols that run relatively slow ( hundred s of kilohertz ) like I2c and SPI. Or some low channel count parallel things like an LCD display in 4 bit or 8 bit mode. Only in a few cases do you need a real analyzer to do true timing or state analysis. and if you need to grab the machine to do state or timing you are fighting a real uphill battle to get yuor system running. it won't be a 2 wire bus but most likely a monster 32 bit bus in a high speed system or it will be a very fast serial bus like sas , pci-x or something else...

I would look at either the 16 bit salae becasue it has buffer memory while still being a streamer. it has excellend software. I know the guys personally i have been at their company on opening day ( they moved to an office at Candlestick park in san Francisco ). Beer and pizza all around. They are really driven and focused on this product.

i personally own a couple of USBee's ( won them at ESC ) a Salae , an MSO7104 ( mixed signal scope : 4 analog 16 digital GHz 4Gs/s ) with the serial decoders software.

the 7104 is used the most as the decoder can do special trigger modes for serial buses that the usb absed systemscannot do. i can tell the scope to only trigger if a write to a particular slave device is beegin performed. this requires special sequential triggering capabilties that the usb products do not , and never will, have (it requires hardware that runs in lock-step with the system under analysis. easy to do in the big chips inside the scope, not easy in a little cpld , impossible emulated on an underpowered little 8 bit cpu)

For the really hard work i have a 16702B with three 16750 blades in it. Those are 68 channel each, 400MHz state and 2Ghz Timing analyzers. These things have fenomenal capabilties, they also cost(ed) a fenomenal price... the machine was over 100K$ new about 10 years ago...
i've used it a few times and it has yielded my investment in it (300$ used, bought from someone who had no clue what it was really worth. company shut down, had to go... sat in a cupboard for 4 years).

[Amarbir[Lynx-India]]

Hi guys, new to electronics . I come from a heating background(i am fix gas boilers in the UK).

what i am after is a way to look at and learn from spi and manchester code. my goal is is to build a modulating room stat basic around a HVAC com protocol (which is manchester coding).

I seen this
http://www.ebay.co.uk/itm/MDSO-LA-20MHz-USB-Digital-oscilloscope-48M-Sampling-16-channel-logic-analyzer-/251119761248?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a77e77760&_uhb=1

it hints at being able to be use with the saleae software. it also have a oscilloscope (I know its not a real oscilloscope but it could be useful).

am i wasting my money with this chinese knock off and go with a better make?

or not to bother at all?

Hello ,
 We Sell The Following As Distributors For India .You Can even Order Directly  .Try This Its Really Nice And Low Cost -> http://www.ideofy.com/

[JoeyP]

2) A better usb based analyzer will have an on board trace buffer and does not rely on the usb transfer speed. Machines like this are the logicport and Chronovu. they solve this problem , but if you run out of memory you run out. done

3) none of the above (1 and 2) are real logic analyzers due to the fact that they neither offer timing (so called timing mode)  nor step synchronisation (so called state-mode). They cannot trap glitches inbetween samples and they cannot listen to an external clock. they have their own internal sample clock and they only look at the points in time given by that particular clock. They are blind inbetween, so you cannot check setup and hold time violations for example and they cannot be driven by a master clock to run in-sync with a system to be debugged. They simply lack the necessary hardware to do this.

Furthermore they cannot do things like sequence triggering nor can they run state logic tat tracks execution and fires the capturing of the abnormal condition.

So do not be misled !

It seems you are the one doing the misleading here. You have lumped all instruments in this class together as if they were identical. They are not. I think you should at least bother to read the specs before making declarations across an entire group of products. I have used many stand-alone analyzers. I have also played with quite a few different PC-based logic analyzers over the years, but only have day-to-day experience with the Logicport, which is a "real" logic analyzer by any reasonable definition.

Timing mode is nothing more than sampling on an internal clock, which virtually all logic analyzers can do (I have never seen any that couldn't do this). The "timing" aspect of timing mode is simply its ability to discern the timing relationships between different signal edges, so its resolution will be determined by the maximum internal sample rate of the instrument.

You stated over and over that "none" of these analyzers can be synchronized to an external clock, but the Logicport does indeed include state mode (using your external clock - not a resampled version of it). I use it in state mode frequently. It also includes some minimal sequential trigger capability.

[nctnico]

I agree. In most cases you only need to sample a few signals at a relatively low rate. Being able to decode I2C, SPI and so on is very usefull but something that old school logic analysers usually won't do without special software. The old school logic analysers are intended to probe and troubleshout parallel data/address busses but the era of the parallel data/address busses is long gone. Everything is USB, SPI and I2C nowadays. Forget about analysing serial busses like PCIex, Sata, etc. These run at several GHz and require expensive probes to start with.

[kg4arn]

Thanks free_electron