Looking for a logic analyzer and scope for less then $400 CDN - Page 1
Forum section: electronics / beginners

author: poot36
author_rank: Frequent Contributor
timestamp: June 30, 2015, 05:36:47 am
content: Here are the minimum specs that I am trying to meet:Logic analyzer:35Mhz state or timingGreater then 1Kb of sample memory32 channels minimumShould come with pods and probesOscilloscope:100Mhz bandwidth preferred 50Mhz ok2 channels but 4 would be great1Gsas preferred but I am not sure what is the minimum that I could get away withenough sample memory for viewing a trigger event a decent amount of time after the triggerI have been looking at the HP 16500 series on eBay but I want to know if there would be a cheaper lighter option from HP or another manufacturer? Shipping from the US to Canada as well as potential boarder charges are also big concerns.

author: Muxr
author_rank: Super Contributor
timestamp: June 30, 2015, 05:54:32 am
content: It's going to be tough finding a decent MSO at that price point. The usual bargain suspects:- Owon: OWON MSO7102T 100MHz ~$800 (ebay)- Rigol: Rigol DS1052D $610 (Tequipment, you can ask for the discount in the discount thread which will lower it a bit).- Siglent: Siglent SDS2102 $1000- Hantek: Hantek MSO5202D $450 (http://www.ebay.com/itm/Hantek-MSO5202D-200MHz-2-Channel-1GSa-s-Oscilloscope-16CH-Analyzer-/271527662486?pt=LH_DefaultDomain_0&hash=item3f384f5396)I have no experience with Hantek but on paper it looks like a decent scope for the price. Not familiar with HP MSOs (mixed domain scopes) in the HP 16500 family. All Ebay returns is dedicated logic analyser but no scopes.MSOs are nice, but if you're going for bang per buck, getting a Seleae clone off Ebay and the Rigol ds1054z is probably your best option. ds1054z is a good scope and you have 4 channels on it with LA decoding. And the cheap Seleae clone isn't going to break the bank. That option with the Tequipment discount might be just under $400.

author: poot36
author_rank: Frequent Contributor
timestamp: June 30, 2015, 06:53:04 am
content: The problem with most USB logic analyzers is the sampling rate and the amount of channels. I need at very minimum 24 channels to try and fix a broken SNES (8 bit data bus and 16 bit address bus) with a clock speed of around 3.5 Mhz. The HP 16500 series take plug in modules and can have a scope option fitted to them. There are also other HP non modular models that have a 2 channel scope built in along with the logic analyzer.

author: coppice
author_rank: Super Contributor
timestamp: June 30, 2015, 07:08:51 am
content: 3.5MHz is extremely slow, so USB logic analysers have no problem there. While a lot top out at 16 channels, there are 32 and 34 channel ones around, that aren't too expensive. For capturing from an address and data bus the biggest weakness of most modern logic analysers is the lack of clocked state capture, which the old HPs are very good at.If I had $400 to spend to deal with your problem I would get a Rigol scope and a 34 channel USB logic analyser. Even cheap analysers have considerable capture depth these days, even though they don't always have the greatest software. I would use capture depth to mitigate the lack of clocked state capture.

author: poot36
author_rank: Frequent Contributor
timestamp: June 30, 2015, 07:23:19 am
content: I do agree that 3.5 Mhz is slow but I have read that you want to have 10 times the sample speed for an proper signal capture. There is also a 24Mhz master clock in there as well so I do not know if that will need to be measured as well or not. I do know that the SNES crashes practically at startup and sometimes does not even start at all until the reset button is pressed so I don't think I need massive sample depth. I also want something that will last a fairly long time and I am not sure that I should trust stuff from China just yet. My experience with a Rigol 1052E was not a good one (bad menu design and glitches even reseting most of my settings back to defaults for no apparent reason and the scope was turned on for less then 4 hours!) Also can the USB logic analyzers decode a 8 bit word into hex in real time?

author: Muxr
author_rank: Super Contributor
timestamp: June 30, 2015, 02:29:44 pm
content: Quote from: poot36 on June 30, 2015, 07:23:19 amI think the rule is different for LAs. As you're not sampling the whole wave, you're just sampling at the clock. So as long as you can trigger on the clock you should be fine.Saleae's Logic 8 can capture 25Mhz signal.

author: Bud
author_rank: Super Contributor
timestamp: June 30, 2015, 02:46:20 pm
content: Google for "ve3kh for sale", he has an Agilent MSO listed. More expensive than your price range though but it is Agilent.

author: Lightages
author_rank: Unknown
timestamp: June 30, 2015, 07:31:02 pm
content: Who said 3.5MHz? The OP asked for 35MHz.

author: Muxr
author_rank: Super Contributor
timestamp: June 30, 2015, 08:36:39 pm
content: Quote from: Lightages on June 30, 2015, 07:31:02 pmOP revised and referenced his original figure to 3.5Mhz multiple times. What am I missing?

author: poot36
author_rank: Frequent Contributor
timestamp: July 01, 2015, 12:27:23 am
content: Sorry about the confusion. As far as I know the signals that I am trying to measure are 3.5Mhz and below but I was under the impression that just like a scope you need 10 times the sample rate to get a good signal. If I do not then what level of over sampleing do I need if any? Is it possible to connect 2 or 3 of the cheap ~$10 8 channel USB logic analyzers to the same computer and have the software use them as a single 16 or 24 channel logic analyzer? I have also looked at the 32 channel OLS logic analyzer for $50 but I am not sure that the software will do what I want (convert the data to hex) and looks complicated to setup. I will look at the more expensive scope as well.

author: miguelvp
author_rank: Super Contributor
timestamp: July 01, 2015, 12:39:44 am
content: Maybe this will suit your needs:http://www.digilentinc.com/Products/Detail.cfm?Prod=ANALOG-DISCOVERYEven at full price is a good deal but if you can get the academic discount then it's a better deal.Windows only and their SDK is x86 only and no source but not a terrible API

author: Muxr
author_rank: Super Contributor
timestamp: July 01, 2015, 01:01:19 am
content: Quote from: poot36 on July 01, 2015, 12:27:23 amObserving a signal to determine the fidelity of it is one thing. This is where you look at the shape of the signal, things like overshoot, ringing, glitches.. etc. Yes for that you need a scope with a much higher frequency than the signal observed, because the signal itself has higher frequency components in it you want to see.But if you trust that the signal is good, and you just want the data that signal is carrying, the individual 1s and 0s. This is what an Logic Analyser does. Then no you don't need to oversample by a lot. Usually the specsheet of the logic analyser lists the max frequency of the signal it can handle and you should be good if the signal you're analysing doesn't exceed that.I don't know about other USB based logic analysers out there. I've only used the Saleae (well and bitscope), which has very decent software, the reason why it's popular. And it just so happens that you can get cheap clones compatible with their software for peanuts.I don't think you can hook up multiple LAs to it to form a one big one. But you could probably cheat with a VM and have two different copies running with USB bypass in order to use multiple units. If you trigger them both off the same signal, you should be able to observe the result in the same time period. It just won't be as convenient.

author: NoItAint
author_rank: Contributor
timestamp: July 01, 2015, 03:16:27 am
content: This is well worth the 15 minute investmentI was thinking I wanted MSO, but for the price a good 4-channel with serial decode is going to be my primary choice.My problems are usually signal integrity related from my sloppy work.MSO is still a good choice for many. Depends on what you need to do - most of the time.

author: poot36
author_rank: Frequent Contributor
timestamp: July 01, 2015, 04:14:18 am
content: You have a good point there, I totally forgot that eevBlab. I found a 34 channel usb logic analyzerhttp://www.ebay.com/itm/34CH-125MHz-PC-USB-Logic-Analyzer-34-Channel-support-I2C-SPI-UART-PWM-Hot-/321460274016?pt=LH_DefaultDomain_0&hash=item4ad8868360#ht_3493wt_1363but I am not sure if the 100K input impedance will be a problem. This onehttp://www.ebay.com/itm/HANTEK-LA5034-34CH-500MHz-USB-PC-Digital-Logic-Analyzer-CAN-I2C-SPI-RS232-/191583449652?pt=LH_DefaultDomain_0&hash=item2c9b437234#ht_3936wt_1140has a 200K input impedance but I can not tell if it will do hex decoding whereas the other one will.

author: poot36
author_rank: Frequent Contributor
timestamp: July 03, 2015, 12:22:44 am
content: Ok, I think I have come up with a plan, get a USB based 34 channel logic analyzer for around $100 and spend the remaining $300 on the scope. Are there any $300 scopes that preferably have 1Gsa/s sample rate and 100Mhz bandwidth and enough memory to display a smallish power supply cap charging up? It would only need to be 2 channel.

author: DIPLover
author_rank: Regular Contributor
timestamp: July 03, 2015, 05:14:49 pm
content: Beware USB "logic analyzers" like the saleae, are not really LAs as they don't do state analysis.When first invented, they were called "logic state analyzers", and they were used to debug minicomputers and micros, when the ability to watch signals go from the processor to the external memory bus and peripherals was paramount.Their importance has faded a lot now with microcontrollers, which have poor observability.I guess your SNES debugging would benefit from the use of a "proper" logic analyzer.Please pm me where in Canada you are located, I have a spare 34 channels 100MHz state/500MHz timing HP1660 series that works like a charm and could potentially help you.

author: poot36
author_rank: Frequent Contributor
timestamp: July 04, 2015, 03:57:14 am
content: PM sent.

author: poot36
author_rank: Frequent Contributor
timestamp: July 06, 2015, 06:11:58 am
content: Well this is annoying, almost all of the logic analyzers on eBay within my price range do not come with the breakout pods. Is it possible to build my own pods or am I just asking for trouble? It will cost me close to $80 or so if I need to get the pods separately. I have seen online that you can use standard (80 pin) IDE cables to connect the logic analyzer to the pods but I am not sure even that is a good idea but with the signal speeds that I would be measuring I suspect that would not be a problem.

author: poot36
author_rank: Frequent Contributor
timestamp: July 29, 2015, 02:07:52 am
content: Well I have managed to get a HP 1661C logic analyzer for less then $100 so I guess that I have around $300 left over for a better scope.