Logic Analyzer Choice

[jpanhalt]

I am looking for an inexpensive (≤ $150 USD) logic analyzer and have narrowed the choice to Saleae or Zeroplus cube.

Does anyone have any comments, recommendations, or experience to relate about either vendor's offerings?

Main use will be as an adjunct to simulation with PIC's. Right now, the only protocols I have experience with are USART and SPI.

Thank you.

John

 

[Ian Rogers]

Have you not got a pickit2???? Its logic tool is quite good!!! 4 channel digital out and 3 channel digital in....

 

[jpanhalt]

No PK2. I was too late to the scene. Microchip sells a stand alone analyzer for about $50. It also sells the Saleae. I have read excellent reviews of the Zeroplus cube.

John

 

[Ian Rogers]

No PK2. I was too late to the scene.

Even the clones do the logic bit.... I have also made several clones... If you keep to the PK2 schematic, you have basically got one..

Some logic analyses have too many channels and it gets messy!! Only my opinion...

 

[Tony Stewart]

1st define the smallest glitch you expect to capture, understand that glitches can be ns or us.

i liked the HP 96 channel for parallel CPU work and Dolch for uC work and Emulation Tech for misc.

 

[Wp100]

As Ian says, even a basic diy pickit2 will do, like bluerooms circuit , you just have to add an extra line from the output connector pin 6 * to RA4 via a 39R resistor to get the third LA input.

* pin6 as shown on the original Pk2 User Manual schematic

 

[Tony Stewart]

This one fits your budget https://www.bitscope.com/software/logic/ and packed full of software features for SPI , Canbus etc. starting at $145

 

[Wp100]

Cannot speak from experience, but the PC based LAs like the BitScope do look good, but if you investigate a certain AU based site geared to test equipment they do pan most such PC based units.

Their bottom line is to buy one of these, which to be honest would probably cost the same or less as to build the very simple diy Pk2LA .
Probably find a stockist in the US for a few $ more ..?
**broken link removed**

 

[jpanhalt]

Thanks all for the advice. The "problem" I was trying to trace was the product of my own misunderstanding. As background, I set up an AMS AS5048A with an SPI interface to a mid-range PIC. It was my first and so far only SPI interface. The data (14-bit) looked great. But, I misunderstood what the parity bit was doing. To quote the datasheet:

Bit<15> is the parity bit, but because it was called an "alarm" bit, I thought it was a bit to be avoided and was trying to find out what the heck was causing it. After a week, I wrote AMS and the reply was simple. It is not an alarm bit. It is just a bit added to always give even parity (duh). I inserted a little code to calculate the parity for the two-byte transmission and after quite awhile of running real time, there was not a single error. In simulation, the parity bit flipped as needed to give even parity. Live and learn.

In thinking about all the things I tried and time wasted to fix a non-existent timing error, I still plan to get a logic analyzer sooner rather than later. I listened to Dave's EEVBlog#44 and got very little out of it. After reading what I could and comparing specifications, the Zeroplus #16032 at about $130 seems worth a try. The biggest complaint has been its manual's English, which didn't seem all that bad. Maybe participation on ETO is good training for that.

Regards, John

 

[Tony Stewart]

If you need pdf translation services, google's works. Also the bitscope runs on Raspberry Pi.
https://www.bitscope.com/blog/EJ/?p=EK07B

 

[Wp100]

If you need pdf translation services, google's works. Also the bitscope runs on Raspberry Pi.
https://www.bitscope.com/blog/EJ/?p=EK07B

Out of interest , have you actually used one of those Bitscope Micros , EEVblogs original post on it is several years old, wondered if you have any first hand experience and views this current version ?
Read so many downers about PC LAs but clear quiet a few folk had not actually used one.

Would not have thought the likes of Farnells UK would be stocking 5,853 of them if they were useless..... would upset their trade customers if they were pups.

 

[Tony Stewart]

Out of interest , have you actually used one of those Bitscope Micros , EEVblogs original post on it is several years old, wondered if you have any first hand experience and views this current version ?
Read so many downers about PC LAs but clear quiet a few folk had not actually used one.

Would not have thought the likes of Farnells UK would be stocking 5,853 of them if they were useless..... would upset their trade customers if they were pups.

No 1st hand info , but if one is aware of test probe good practices and glitch capture, this tool has many features related to this that lead me to believe it has been well thought out for reliable capture. The software is friendly and has a large user forum. And if it runs on Pi, it must be low overhead.

I never pay attention to EEV's video's , although I have seen parts of a few. ... good for others to learn, perhaps. I had the luxury once of a large budget for test equipment, that would choke any university's budget. Plenty of Tek Diff probes with 0.5pF input, many LA's, and NA's, SEM and Modal Analyzer too for 3D resonance or transfer functions, Bode Plotters, Huntron trackers.

My favorite tool, was a simple analog Tek scope with XYZ inputs. I would do things like put the servo loop of a voice coil from a HDD into the scope and feed it out the back of the scope on CH1 and then back into the drive so I could qualify a magnetic head supplier for adjacent track interference performance by moving the vertical axis to shift the servo and heads in or out and then inject a sinewave for X and Y and get the actual signal vs offset profile.

For Uarts and stuff in the 70's I used a cassette tape for 9600 baud capture to transport 6800 code from the programmer who was a university professor that taught "compilers" for a big project we could not handle. I would make my own serial port 3-way Y cable and monitor traffic between two computers onto one dumb CRT and verify SCADA performance in my design.

 

[Wp100]

No 1st hand info , but if one is aware of test probe good practices and glitch capture, this tool has many features related to this that lead me to believe it has been well thought out for reliable capture. The software is friendly and has a large user forum. And if it runs on Pi, it must be low overhead.

I never pay attention to EEV's video's , although I have seen parts of a few. ... good for others to learn, perhaps. I had the luxury once of a large budget for test equipment, that would choke any university's budget. Plenty of Tek Diff probes with 0.5pF input, many LA's, and NA's, SEM and Modal Analyzer too for 3D resonance or transfer functions, Bode Plotters, Huntron trackers.

My favorite tool, was a simple analog Tek scope with XYZ inputs. I would do things like put the servo loop of a voice coil from a HDD into the scope and feed it out the back of the scope on CH1 and then back into the drive so I could qualify a magnetic head supplier for adjacent track interference performance by moving the vertical axis to shift the servo and heads in or out and then inject a sinewave for X and Y and get the actual signal vs offset profile.

For Uarts and stuff in the 70's I used a cassette tape for 9600 baud capture to transport 6800 code from the programmer who was a university professor that taught "compilers" for a big project we could not handle. I would make my own serial port 3-way Y cable and monitor traffic between two computers onto one dumb CRT and verify SCADA performance in my design.

Thanks for that, interesting.
I only have a pensioners budget and just have my trusty old analogue Hameg scope.

Seems the reason Farnells stock so many of the Bitscopes is that they are partners.
Will have to look in the forum you mention and do a bit more reading /searching as it does seem to offer a lot of useful functions for the basic diyer.
**broken link removed**

 

[be80be]

Lol you only need a pic 18f2550 a 100 nf cap and 20 mhz crystal and 2 18pF caps and old usb cord load the pic with the pickit 2 frimware and you got a 4 Chanel logic tool for about 8 dollars

Oh and a 10 k to pull mlcr up

 

[Wp100]

John,

You seemed to be looking at mid range analyzers , though not sure if you are still going to get one ?

I'm also a novice with LAs, and have only tried the LA function within the PK2, which does work but seems very limited.

Decided to get one of those ebay $10 clones which runs on the free Saleae software.

Thought you might be interested to see my first views with both devices, its just monitoring the Serial Out and Clock spi signals from an Arduino to lcd.
Its just the simple monitoring of the two lines, have still to try the Protocol Analyzer functions.

The PK2 LA is very basic but it also has the Logic Tool facility to set and test i/o lines.

There are two shots of the Saleae software v 1.15 that the clones say to use, but seems it also works with the latest v 1.34.
Both clearly way ahead of the Pk2 in features and the obvious fact you can see the signals clearly on a full screen.

As I you probably have already found you can download the Saleae software and run it without the actual hardware box by using its inbuilt Simulate function to see how it works.
https://downloads.saleae.com/betas/1.1.34/Logic Setup 1.1.34.exe

**broken link removed** **broken link removed** **broken link removed**

 

[jpanhalt]

Thanks for the follow-up. I went ahead and ordered the Zeroplus 16032 and received it last Thursday. Looked at a tutorial, but haven't had a chance to actually run it. I will capture some screen shots when I do run it and will post them here. I suspect the basic functions will be pretty much the same. But, we'll see.

John