Logic Analyzer

RE: Logic Analyzer

saadtiwana_int — Fri, 21 Aug 2020 04:35:02 GMT

Hi Brian,

It depends on your requirements of-course. I have been using a Saleae Logic Pro16 for the past 5 years and can definitely recommend it. I am not sure how high you need to go in terms of frequency requirements for your projects, but as a logic analyzer, it will definitely cover a lot of protocols.

Another tool that i have used and would recommend is the "USBee" devices. Their protocol decoder feature is especially really good! You should check it out.

Lastly, if there are certain protocols you work with frequently, you should check compatibility on any device that you're considering buying. Not every device will support everything, while the common protocols (UART, SPI, I2C, etc ) are supported by everyone.

Lastly, note that the logic analyzers are not very good as oscilloscopes, even though some of them claim to do that too.

Hope it helps,

Saad

RE: Logic Analyzer

michaelkellett — Thu, 25 Jun 2020 14:30:37 GMT

I haven't used a stand alone logic analyser for a while now - the ones built into scopes have made them unnecessary.

Prior to that my favorite (by a large margin) was a Zeroplus model. You can still buy these from the Debug Store.

https://www.thedebugstore.com/test-equipment/logic-analysers/16-channel/lap-c-16128-logic-analyser-zeroplus

I think this is the current version of the one I have.

I used it to debug my first FPGA SDRAM interface - so it's capable of real work.

RE: Logic Analyzer

shabaz — Thu, 25 Jun 2020 11:53:23 GMT

Hi Brian,

There's some on the Farnell website. If you want to do very specialist decodes, or high speed protocols, then you need to check if that's supported. Some specialist protocols end up needing particular gear.

Also many oscilloscopes have integrated logic analyzers too (often known as a 'mixed signal oscilloscope'.Some will handle a good suite of protocols, although it may be licensed. It has the advantage that the electrical properties of the bus can be examined too of course. Even without mixed signal capability some serial buses are easy to mentally decode from the 'scope trace. You don't mention it, but if you don't have a 'scope, that's perhaps a better instrument to acquire first. Picoscope have low-cost USB products (ballpark $100 USD) that have in-built serial decoding. The Picoscope software is free to download and you can explore the protocols available.

There's some open source logic analyzers (they use open source code, PulseView) so you can probably download the software and try it out, and check the list of protocol decodes available too, to see if the ones you need are available.

The open source logic analyzers are mostly similar to the basic 'Saleae Logic' product. That manufacturer sells other logic analyzers too.

There's also an open source ready-built product called Open Workbench Logic Sniffer, and there's another one based on an FPGA board. It too works with the Pulseview software.

Some logic analyzers may allow use with the free Wireshark software for certain protocols.

For low-speed inter-IC buses such as I2C and SPI, I tend to use an oscilloscope or the open source logic analyzer. Once the physical connections are made and the bus is functioning electrically, then I try to move to higher-level debugging (such as printf statements in the code) as quickly as possible however.