Looking for an logic analyzer with a lot of channels, not speed (State analysis) - Page 1
Forum section: electronics / testgear

author: robindegen
author_rank: Newbie
timestamp: March 21, 2019, 05:03:30 pm
content: Hey all,Short backstory:I have embarked on the crazy project of building a CPU from scratch with mostly 7400 series components (5v cmos, not ttl). This has been going on for over a year.I have a cheap Kingst LA2016 usb logic analyzer which is OK but not great.I have also built my own basic analyzer based on a few MCP23017 which gave me a lot of channels, but this is a bit wonkey and I have to write my own software suite (which comes with it's own set of bugs and problems)What I'm really looking for is an analyzer with a lot of channels (preferably 100+). The reason for this is I want to be able to debug my CPU at various locations completely and a single 16 channel analyzer just won't cut it.I also need to be able to group channels together as a single value: so take 16 bits and display it as a single hex value for example, and preferably name it.I have been looking at a second hand HP Agilent Keystone 1670G which seems to fit everything I need. However there must be a cheaper solution. I am not at all interrested in speed/performance! Just as many channels as possible and being able to group them to view them as values (to monitor values of registers etc.)Since I have full control over my cpu's clock, it's even fine to run the whole thing at 1hz if needed (as a figure of speech... faster is better for future projects but just to indicate I really don't need any performance here).What I'd prefer is a USB based setup with some good software, preferably software with some API that I can use to get the features I want (decoding/debugging).So to summarize what i'm seeking:- Logic analyzer with >= 100 channels- Doesn't have to be fast (even 1hz is fine)- Would be nice if it has an external trigger that I can just hook up to my slow clock (State Analysis, not timing)- Should support 5V CMOS and 5V TTL levels, 3.3v is nice to have.- Should have a decode view as i'm interrested in values of entire registers, not signal timing (i have my analyzer on my scope for this).- Software doesn't have to be amazing if it has some API that I can use to achieve this- I don't want to build something from scratch. I have enough projects as it is. I toyed around with some IO extenders and sending that over rs232, but I'd prefer an already working solution.- Don't really care about the budget too much if it's < 1000euros. If it's higher, I'd consider it based on how good of a solution it is.- I'm in the Netherlands so anything from within Europe is prefered, unless it's through ebay's international program where customs fee's etc are paid up front. I don't want to get any nasty surprises.Hopefully somebody can help me! If not, I might still go with an HP Agilent Keystone 1670G at some point.

author: 0culus
author_rank: Super Contributor
timestamp: March 21, 2019, 05:09:51 pm
content: One of the big pitfalls with logic analyzers is that, while you can get them for a good price, the cost of all the probes, flying leads, and clips you'll need is substantial.  if the one you buy doesn't have all of them.My logic analyzer is a Tektronix TLA 715 mainframe that I bought from a guy on ebay who refurbishes them, updates software, etc. It has 2 TLA 7N4 136 channel modules. The only inconvenience I've found is that, on these modules, you cannot adjust the trigger point for ultra high speed "magnivu" acquisitions. If you don't care about that, they work fine! I bought it with a pair of P6417 probes + flying leads and clips. Getting enough probes to populate the whole instrument is going to be expensive, but I'm going to bite the bullet eventually. Fortunately, for the project I'm currently using it for (FPGA based) I don't need very many channels!It's fully featured and the TLA software does all the things you mentioned.  it's also possible to find a DSO module for these instruments. So you could have 136 logic channels and a reasonable (but not great) DSO.

author: nctnico
author_rank: Super Contributor
timestamp: March 22, 2019, 02:21:43 pm
content: The Tektronix TLA715 is a good choice. The probes for the TLA7AA4 modules are dirt cheap and a simple adapterboard can be made to attach flying leads to them. The Tektronix logic analysers also have a programmable trigger state machine. I have used this feature a couple of times to find extremely elusive software bugs.

author: artag
author_rank: Super Contributor
timestamp: March 22, 2019, 07:47:55 pm
content: HP16500 series are also pretty cheap, especially the A and B models. HP1650 or 1660 if you want something more compact.

author: gslick
author_rank: Frequent Contributor
timestamp: March 23, 2019, 01:27:00 am
content: Quote from: artag on March 22, 2019, 07:47:55 pmOne of the main limitations of the HP 1650 series is a 1K sample depth per channel, and on the HP 1660 series it is 4K sample depth per channel.The HP 1670 series have at least 64K sample depth per channel, and up to 2M sample depth per channel. It is 1M sample depth an all 1670E while the 1670A, 1670D, and 1670G and sample depth options. A 1670E would be better than a 1670G without any options.HP 1670A mono CRT, 64K sample depth standard, 500K sample depth with Opt 030 (1996)HP 1670D mono CRT, 64K sample depth standard, 1M sample depth with Opt 30 (1997)HP 1670E color LCD, 1M sample depth standard (1999)Agilent 1670G color LCD, 64K sample depth standard, 256K sample depth with Opt 001, 2M sample depth with Opt 002, Scope with Opt 003, PatGen with Opt 004 (2000)1670A, 1670D, 1670E, 1670G 136 channels1671A, 1671D, 1671E, 1671G 102 channels1672A, 1672D, 1672E, 1672G 68 channels1673G 34 channelsFor the 16500 series, the main limitation of the 16500A is that it is dual floppy based, with no hard drive. That excludes support for the 16554A, 16555A/D, 16556A/D, 16557D with 1M or 2M sample depth. There is the 1K sample depth limitation of the 1650 series using 16510A/B modules, or the 4K sample depth limitation of the 1660 series using 16550A modules. (There are the 16540D and 16541D modules with 16K sample depth, and the 16542A module with 1M sample depth, but those are much less common than 16550A modules). The 16500A also does not have a LAN option. Both the 16500B and 16500C have hard drives. LAN is optional on the 16500B and standard on the 16500C.If you are not local to pick up a 16500 series, the cost to pack and ship the system may exceed the value of a 16500A system. Shipping relative to the overall value should be lower on a 16500B or 16500C system depending on the modules and accessories included with the system.Depending on your location you might even find better deals on a 16700 series system. Someone local to me has listed a bare 16700A on eBay for $20 a few times with no takers. Even at that low price I don't need another 16700A to make it worth my time to pick up that one.If you don't have a lot of bench space then a 1670 series would be better than the larger and heavier 16500 and 16700 series, if you can find one available in your price target.I'll leave the Tektronix opinions to the Tektronix experts.

author: xwarp
author_rank: Frequent Contributor
timestamp: March 23, 2019, 01:32:41 am
content: Where are you located? I have a HP 1660ES that needs a new home.

author: HalFET
author_rank: Frequent Contributor
timestamp: March 23, 2019, 01:35:28 am
content: Valid points gslick, and don't forget that you need a computer with a built-in floppy drive and a working pre-windows vista installation to flash the disk images onto the floppies, because HP couldn't quite agree with IBM at the time. And due to the unique way USB floppy drives on windows work you can't flash the images using one of those.One nice thing about the 1652B that I have here are the two scope channels, they're surprisingly useful on certain occasions. Also for HPAK LAs it's often cheaper to buy up second-hand LAs until you have a full set of probes than it is to buy the probes separately. And you can find the flat HP-style clips on Aliexpress if you look around a bit.

author: 0culus
author_rank: Super Contributor
timestamp: March 23, 2019, 01:38:23 am
content: Quote from: nctnico on March 22, 2019, 02:21:43 pmI forgot about the trigger state machine, but absolutely, this is another feature I've found useful. Sometimes the canned triggers work, but when they don't, having access to a full state machine makes setting up what you need a lot easier.

author: gslick
author_rank: Frequent Contributor
timestamp: March 23, 2019, 02:01:48 am
content: Quote from: xwarp on March 23, 2019, 01:32:41 amThat is an excellent question. The original poster should state his general location. I assume somewhere in Europe as there was a budget figure of <1000euros. Shipping a logic analyzer from the US to Europe is probably not cost effective for most older systems.Back to the HP 1660 series:HP 1660A mono CRT, 4K sample depth, floppy only, no LAN option (1994)HP 1660AS add 2 channel, 1 GSa/s, 250MHz, 8K sample per channel scopeHP 1660C mono CRT, 4K sample depth, hard drive, LAN with Opt 015 (1996)HP 1660CS add 2 channel, 1 GSa/s, 250MHz, 8K sample per channel scopeHP 1660E color LCD, 4K sample depth, hard drive, LAN standard (1999)HP 1660ES adds 2 channel, 2 GSa/s, 500MHz, 32K sample per channel scopeHP 1660EP adds 32 channel 256K vector depth per channel pattern generator1660A, 1660AS, 1660C, 1660CS, 1660E, 1660EP, 1660ES 136 channels1661A, 1661AS, 1661C, 1661CS, 1661E, 1661EP, 1661ES 102 channels1662A, 1662AS, 1662C, 1662CS, 1662E, 1662EP, 1662ES 68 channels1663A, 1663AS, 1663C, 1663CS, 1663E, 1663EP, 1663ES 34 channelsAn HP 1660ES would be a portable equivalent of a 16500C mainframe with a 16550A logic analyzer module and a 16534A scope module. A nice portable system with a built in 2 channel scope, if 4K sample depth of 136 channels is sufficient for your logic analysis needs.

author: robindegen
author_rank: Newbie
timestamp: March 23, 2019, 01:59:26 pm
content: Thanks for all the information so far guys. I'm in the Netherlands so anything from within Europe is prefered, unless it's through ebay's international program where customs fee's etc are paid up front. I don't want to get any nasty surprises. I'll edit my original post with this info.A HP1660 looks quite interresting to. These seem to all require a floppy disk to boot, am I reading that correctly? How hard is it to get these replaced? Floppies are notorious for breaking in my experience which would essentially brick the machine? I did find that keysight has recovery floppy images on their website but i'd need to buy some usb floppy disk drive since I have nothing with floppies anymore.Quote from: xwarp on March 23, 2019, 01:32:41 amThat might be interresting depending on (shipping) costs. I've found a few on ebay (like HP 1660A for about 300$ including shipping and customs charges)

author: gslick
author_rank: Frequent Contributor
timestamp: March 23, 2019, 05:43:12 pm
content: Quote from: robindegen on March 23, 2019, 01:59:26 pmThe HP 1660 and 1670 portables all boot from flash ROM. All 1660 and 1670 models have hard drives, except the 1660A models. The flash ROM does not contain the PV (Performance Verification) files so if you want to run the self tests you need to have them on the hard drive or on a floppy. One of the first things you should do when you receive a system that is new to you is to run the PV tests to make sure there are no obvious hardware failures. Otherwise the floppy and hard drives are only needed for storing configuration and data files.In addition to being the only models without hard drives, I believe the 1660A models are the only ones that do not support MS-DOS format floppies, only LIF format, and the only ones with HP-HIL mouse/keyboard instead of PS/2. Also, all 1670 models and the 1660E models, and optionally on the 1660C models have LAN support. That is not an option on the 1660A models. The LAN interface is very useful to have for transferring configuration and data files to and from the analyzer, capturing screen shots from the analyzer, and remotely controlling the analyzer.In summary if you are looking at HP 1660 and 1670 series, the 1660A models are the least desirable and any later 1660 series model or 1670 series model is better. So take that into account if you were making a choice between one model or another. Or course there are other factors too. If you absolutely need more than 100 channels then you would need a 1660 or 1670 with 136 channels, or a 1661 or 1671 with 102 channels. A 1662 or 1672 model with 68 channels or a 1663 or 1673 model with 34 channels would not meet your requirements.

author: xwarp
author_rank: Frequent Contributor
timestamp: March 23, 2019, 06:14:43 pm
content: My 1660ES has the floppy drive in it, all cables and some discs. Not sure what is on the discs, but it boots up and runs pretty nicely.I've never shipped anything this big overseas, and I would not be surprised if it were prohibitive.

author: 0culus
author_rank: Super Contributor
timestamp: March 23, 2019, 07:34:11 pm
content: Quote from: xwarp on March 23, 2019, 06:14:43 pmShipping large heavy instruments within the US is expensive...overseas is going to be a good fraction of the purchase price no doubt.

author: artag
author_rank: Super Contributor
timestamp: March 23, 2019, 08:50:17 pm
content: Quote from: gslick on March 23, 2019, 01:27:00 amAn excellent summary, thanks for that. The older analysers are definitely a choice for cheap width : but not for depth.We used to manage with them, though - and one of the reasons is that state analysis is much more precise than timing analysis. It is possible to define trigger conditions and trigger sequences that allow the analyser to capture a particular event. With the common use of microcontrollers where much of the internal state is hidden, it's not possible to do this and the answer is deep capture and post-analysis. The OP wanted a state analyser and although I'm not familiar with the state of the art now, my impression is that state analysis is not such a popular tool any more.I do have a 16500B (I'd prefer a 16500C) with a full load of scope, timing, fast timing and word generation options which cost me a few hundred pounds in the last 10 years despite the main parts being shipped from the USA to UK. It wouldn't fetch even that now on ebay but I suspect it would do a good job for the OP's requirements while being pretty poor (and hot, and noisy!) for most modern labs.