Affordable Logic Analyzers?

[cbmeeks]

I was watching a YT video the other day about a $75 (16 channel) logic analyzer. Inside it was driven by an FPGA and some standard USB chip (not much else other than passives).

Of course, the bulk of this tool was in the software side.

I'd like to get me a logic analyzer but I can't justify a lot of money. I'm thinking "hundred-ish". Have you guys had any experience with these?

FWIW, most of the time I would be using it to debug vintage computers and my own SBC's (8-10 MHz tops).

Any recommendations would be appreciated.

[floobydust]

Good question... I still have a couple older (60MHz bandwidth) Tektronix scopes, so they help quite a bit. Some years ago I picked up a Saleae Logic-16. These are FPGA based and, as noted, heavy on the software side. They are also quite expensive, albeit very well made and well supported.

https://www.saleae.com/

There are numerous el-cheapo clones available which can use the Saleae software... while I personally don't like that pairing, it exists, just that don't expect the same quality, reliability, accuracy, etc. that you would get by buying the real hardware.

Digilient also offer some interesting hardware/software tools these days. Check out the link below.... USB scope and logic analyzer:

https://store.digilentinc.com/analog-di ... er-supply/

Unfortunately, getting good test equipment at sub-hundred dollar pricing limits you to clone hardware from China and pilfering software from other vendors. Hopefully someone else can come up with something more attractive on the pricing side.

[cbmeeks]

I really like the Saleae stuff. I might just save up my blow money and go that route.

[JimDrew]

I have every Saleae model they have made. I am a little surprised to see that the Logic 16 Pro is now $999. I got it when it was first announced for 1/2 that.

Their software is top notch, and the guys there are very responsive to software issues. I just wish they had a simple device that would OUTPUT the same signals coming in (like a playback mode). They have teased that one might be coming for years. I use the USBee SX for that purpose, but it is only 8 channels.

If Saleae had a 32+ channel LA, I would already own it. I just ordered a Hantek 4032L, which is a 32 channel LA. I can use their software or the open source stuff with it.

You can buy the Hantek 5034L, which is a 34 channel LA for under $100 off of eBay. I was too chicken to try it after the reviews I saw. I just need it for slow (6502) signals, so it might work fine for that purpose.

[dmsc]

Hi!

cbmeeks wrote:

I really like the Saleae stuff. I might just save up my blow money and go that route.

I like the sigrok interface (pulseview), so I recommend any cheap logic analyzer that works with it:

-> Cheaper are the 8ch saleae clones, just search aliexpress for "8ch 24m", about US$8.5 shipped.
-> If you go with the bare boards, you can sample 8 channels at 24MHz or 16 channels at 12MHz, for about US$3.5 (like these https://www.aliexpress.com/item/IEZ-USB ... 58835.html ).But those are not protected, so you need to be careful or add resistors.
-> For an advanced model, the mcuprog logic-16 (see at https://sigrok.org/wiki/Mcupro_Logic16_clone ) can sample 16 channels at 16MHz or 3 channels at 100MHz, for about US$35 shipped.

[BigEd]

It must be worth mentioning hoglet's work which allows recovery of 6502 instruction traces and internal machine state using surprisingly few signals:

• A novel 6502 Protocol Decoder for Sigrok

Quote:

The 6502 protocol decoder requires just 12 signals plus ground to be connected: D7..D0, RnW, Sync[see below], Rdy and Phi2. From these, it's able to produce full instruction traces
...
In terms of capture hardware, this should work with anything that is supported by Sigrok that has at least 12 channels and can sample at ~5x the CPU speed.
...
I can't really overstate how useful a tool like is can be in diagnosing misbehaving 6502 systems (old or new). If anyone wants to have a play, I'm quite happy to help answer any questions.

Note that Sync is not strictly necessary, and in fact various signals are optional. From the help:

Quote:

• If phi2 is not connected the capture file should contain one sample per falling edge of phi2.
  If rdy is not connected a value of '1' is assumed.
  If sync is not connected a heuristic based decoder is used. This works well, but can take several instructions to lock onto the instruction stream. Use of sync, is preferred.

[John West]

floobydust wrote:

Digilient also offer some interesting hardware/software tools these days. Check out the link below.... USB scope and logic analyzer:

https://store.digilentinc.com/analog-di ... er-supply/

They also have the Digital Discovery https://store.digilentinc.com/digital-d ... generator/, which is $80 less ($199). By coincidence I ordered one last night. If you've already got an oscilloscope and do mostly digital work, you're not going to miss the analogue features of the Analog Discovery, and for the 6502 the extra 16 channels are going to make life a lot more pleasant.

[GaBuZoMeu]

Some years ago I bought an Intronix Logicport LA 1034 to figure out a strange behaviour of a MC68332 dealing with parallel I/O. The Logicport simply worked as expected.

[BitWise]

I have an original Saleae Logic 8 which is nice but a little temperamental, some Saleae logic 8 clones (half of which work with the Saleae software and half which need Sigrok) and a Hantek 6022B 16 channel analyzer.

The big problem with all of these is that they fail to achieve the maximum USB transfer rate (24 MB/s) so they can't really be used on signals over 8-10Mhz.

The Hantek was a mistake. I thought it contained memory to buffer the USB but it doesn't so the maximum rate is a theoretical 12 MB/s but as most PCs share the USB bus with mice, webcams, keyboards and my PIC programmers.

I'd like a self contained analyzer with some protocol decoders built in. I need one at the moment to watch some serial signals in real time and might waste some cash on one of these ...

https://www.ebay.co.uk/itm/Mini-LA104-L ... 3724817248

.. but really I'd like 32+ signals.

[dmsc]

Hi!

BitWise wrote:

I have an original Saleae Logic 8 which is nice but a little temperamental, some Saleae logic 8 clones (half of which work with the Saleae software and half which need Sigrok) and a Hantek 6022B 16 channel analyzer.

The big problem with all of these is that they fail to achieve the maximum USB transfer rate (24 MB/s) so they can't really be used on signals over 8-10Mhz.

Oh, in my (6 year old) notebook, with pulseview, I always use 24MB/s sampling rate with my Saleae clone, and routinely sample a few minutes at that rate. I use Linux and last pulseview and fx2law firmware.

I understand that old firmware had a bug that prevented using the full bandwidth, bit in mi experience that do not happens anymore.

[JimDrew]

I use 40 MB/S with my Saleae Logic 16 and 100 MB/S with my Logic 16 Pro. No issues at all. The Logic 16 Pro has the USB3.0 interface (dual connectors). Sample rates have never been an issue with my Saleae or USBee products. The Hantek 4032L has 2GB of memory for buffering, but it will also run in stream mode.

I tried Pulseview a few days ago, but it won't work with any of my Saleae products. The only one it recognizes at all is the Logic 16 (not the Logic 8 or the Logic 16 Pro), and selecting it results in Pulseview crashing. I looked at the "novel 6502 Protocol Decoder for Sigrok 6502" info. It requires that you compile it, which I don't want to figure out how to do. If there was some plug-in or something already done, I would LOVE to look at it. Does anyone actually have that working?

[BigEd]

AIUI, Dave's first go at the 6502 protocol analyser was as a Sigrok plugin, but ultimately he wrote a standalone decoder in C - it should be portable and easy enough to build, but if you have difficulty, you can probably get help.

Quote:

... I've re-written this in C, because I was getting frustrated at waiting minutes for the python/sigrok version to run. The C version is ~200x faster, and I'm also much faster at working in C than Python! The code is in it's own github repository now:
https://github.com/hoglet67/6502Decoder

[JimDrew]

I am not much of a 'C' guy. I was hoping that someone had already built a Windows version.

[hoglet]

JimDrew wrote:

I am not much of a 'C' guy. I was hoping that someone had already built a Windows version.

What version of Windows are you running?