When one of my original Logics stopped working, after a little bit of on the phone trouble shooting, they just send me a new one overnight, and even paid for the return shipping for the dead one. I was slightly confused by all those ground wires at first. Documentation is a confusing tangle of wikis and docs and versions, scattered across three different web sites, with redundant or conflicting information, and frequent links to obsolete information. Why should you care about external clocks? Last month the nice folks at Saleae were kind enough to send me a new Logic Pro 8 for review, so I recently had a chance to test the hardware first-hand. Lacking of advanced trigger is a big draw back.
It is part of the second-generation Saleae Logic series, which consists of the Logic 4, Logic 8, Logic Pro 8 and Logic Pro 16. As a test we sniff the serial traffic of an Arduino compatible Nano board from banggood. In my case, I wanted the 32 channels 8088 address and data bus, controls, etc… , otherwise, I would go with a product that seems to get more love from the company. In general, the fewer channels that are used, the higher the sampling rate that the Logic Pro 8 can achieve. We connect Channel 0 of the Logic pro as shown: Note that the schematic above shows the bottom of the daughter board. They were a bit expensive and the software is too simplistic, but they get the job done. It supports external clock sources, and has fairly powerful triggering options, but lacks a state view mode.
Anti-aliasing Filters An anti-aliasing filter prevents frequencies higher than the Nyquist frequency from being sampled. Instead of triggering on an error condition, you could capture 10 million sample points, and then search for the error condition in the captured data. The Pro 8 supports logic levels between 1. Logic Pro 16 produces analog data at a rate of 9. Note that sigrok-util commit 20e302a2 only works Saleae Logic software up to 1. Plugins and Scripting The Saleae client software offers two ways to extend its functionality: protocol analyzer plugins, and client scripting. It may not trigger on the condition, but as long as we can find the condition in the long captured data, it should be as good.
Only along some of them, and then compromise along others. Saleae needs to expand the existing list panel into a full-fledged data view screen, with functionality similar to the waveform view. As a result the total bandwidth has increased 50%, and with it, the number of channels that can be used simultaneously at any given sample rate. The sample buffer holds up to 2K samples, or more if using sample compression. I also bought a counterfeit because I was curious about the hardware differences, and besides they are nice little 8051 boards. No matter, anything they included in the box would likely be out of date by the time it was opened anyway. What were the actual values of A and B at the clock edge? For electronics hobbyists working with relatively slow parallel bus-based systems, the old Logic 16 was ideal.
. Digital and analog sample rates can be adjusted independently, and the total capture length is also selectable. A has a transition shortly before the second rising clock edge, and B has a transition shortly after the edge. In addition, on Logic 8, Logic Pro 8, and Logic Pro 16, each input can be configured to be an analog input, a digital input, or both at the same time. From here you can zoom in and out of the captured waveforms, or pan left and right to view different time periods. Plugins are implemented as C++ shared libraries, and enable the client to be extended to support new protocols, or to add new options to existing protocols.
You can trigger on digital edges and pulses as well as analog voltages and pulses. It is a pretty good device. This is one instance where Saleae may have too much of a good thing, and a bit of extra size and weight might be welcome. The reason why I bought a Logic Pro 16 was to support their good behavior. The absence of robust triggering options might not be too bad if it were possible to search the acquired data for a complex trigger-type event after the fact. I really appreciate the objectivity, and the detail in your review.
Dual-Use Inputs and Signal Integrity To provide optimal signal integrity with a flying lead test probe, each input has a dedicated ground wire. Record To record your digital and analog signals, just press start. The second reason that external clocks are important is correctness of the captured data. The Logic is so small and light, it can get lost on a desk, or pulled off the desk by the weight of the cables attached to it. Filters can have an adverse effect on both gain and phase so this must be carefully accounted for. Most of these only required relaunching the client software, and submitting a crash report to Saleae.
The added analog capabilities of the Logic Pro series are just a novelty. So the order of the pins in the photo is reversed Saleae provides the software which is used to collect and analyse data. Unlike some other logic analyzers that feature external clock and trigger inputs, 8 channels on the Logic Pro 8 means 8 total inputs. The whole setup packs away into a cushioned nylon carrying case. I had initially assumed the analog inputs would be most useful for checking the signal integrity of digital signals — looking for overshoot, noise, or glitches that might cause problems. Buffered logic analyzers contain dedicated high-speed memory for storage of signal data.
By the way, I own two original Logics an a Logic Pro 16. If you like, help me covering my running costs with a dollar or two. But when pushing to higher speeds with tighter timing margins, the lack of an external clock is a real handicap. Imagine that the Logic Pro 8 is sampling these three signals four times per clock period, for 4x oversampling, at intervals shown by the green vertical lines. Only the logic analyzer parts are currently implemented analog sampling is not. The software will figure out the rest and display the relevant measurements. The Saleae engineering team is working on a fix, but for now their advice is to turn off analog channels when using triggers.
The biggest problem with it is that it appears the company no longer updates the software and it is Windows only. With external clocking, samples are taken exactly at the clock edge, and the values captured are those that were seen by synchronous devices at the clock edge. The Saleae client software does have a basic search capability, so for example you can look for all instances where the value 0xC8 appeared on the serial port. For Logic Pro 16, this is an awesome 9. The wires are terminated with a female 0.