logic analyzer

77 Articles

Old Logic Analyzer Becomes New PC Case

December 31, 2017 by 26 Comments

There are a lot of cool ways to wrap a case around your custom PC build. But the off-the-shelf stuff doesn’t really set your machine apart from the herd, no matter how many RGB LEDs you put inside. If you really want to stand out, think out of the box, and build your PC into the case of an old logic analyzer.

Looking for a little retro cool factor, [Bob Alexander] turned to the world’s boneyard, eBay, and rounded up a dead H-P 1653 logic analyzer. State of the art in 1989 but not worth repairing by [Bob]’s lights, he removed the original 10″ CRT to make room for an alternate display. After a bit of experimentation, he settled on an LCD panel mounted behind a sheet of acrylic that he thermoformed to the shape of the CRT face. All the original guts were removed to make way for the motherboard and power supply, and a custom PCB to interface the original keypad and rotary encoder into the PC. The old buttons now launch various programs and the encoder acts as the PC volume control. The floppy drive made way for a USB hub, the BNC connectors became power and reset buttons, and a photo taken through the CRT bezel before the electronics were removed provides a window into the soul of the original instrument. It’s a really nice build, and totally unique.

Need some inspiration for your custom case mod? This wall-mounted render farm is pretty snazzy. Or perhaps you’d prefer something more apocalyptic, like this ammo can PC.

Logic Analyzer Pushes The Limits Of Miniaturization

December 22, 2017 by 9 Comments

Careful not to sneeze while using this diminutive logic analyzer — you could send it flying across the bench.

Undertaken more for the challenge than as a practical bench tool, [Uwe Hermann]’s tiny logic analyzer is an object lesson on getting a usable circuit as small as possible. Sure, some sacrifices had to be made; it’s only an eight-channel instrument without any kind of input protection at all, and lacks niceties like an EEPROM. But that allows it to fit on a mere 11 x 11-mm fleck of PCB. That’s a pretty impressive feat of miniaturization, given that the Cypress microcontroller running the show is in QFN package that takes up 64-mm² all by itself. A micro-USB connector takes up much of the back side of the board and allows the analyzer to talk to sigrok, an open-source signal analysis suite.

Everything about the project is totally open, including the PCB files, so you can build your own if you feel up to the challenge. We’d strongly suggest you check out this primer on logic analyzers first, though, especially since it focuses on the capabilities of the sigrok suite.

DSLogic Plus Teardown And Review

August 24, 2017 by 14 Comments

The DSLogic open source logic analyzer is on its second release (the plus version) and [OpenTechLab] has a comprehensive review of the new model, which, unlike the original model, includes a different method of connecting probes and provides a separate ground for each input pin.

The device is pretty simple inside with an FPGA, a RAM, and a USB microcontroller. There’s also a configuration EEPROM and a switching power supply. The device stores up to 256 megabits internally and can sample 400 million samples per second on 4 of its 16 channels. [OpenTechLab] even puts the board under a microscope and maps out the input circuit.

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Using A Logic Analyzer To Generate Screenshots From A Game Boy

August 1, 2017 by 9 Comments

Wouldn’t you like to go back to a dead handheld and extract the proof of your 90s-era high scores? Of course you would.

[svendahlstrand] bought his first logic analyzer, a Logic 8 from Saleae and decided to play around with an old Game Boy. He opened up the handheld with a tri-point screwdriver and hooked six wires up to the LCD data bus, generating screen shots from the logged data. He got screens from Solomon’s Club, Mole Mania, Kid Dracula, and more.

The first few attempts were fraught with mishap as [sven] worked to figure out the settings of his new analyzer. In one instance he had the DATA 0 and DATA 1 signals reversed, also reversing two of the gray values. After figuring it out he posted his LCD sniffing tutorial to GitHub, where he also has a C program for manually piecing together the screen shots, pixel by pixel.

Thanks to [sven] for posting this project to our recent Everything You Need to Know About Logic Probes post.

 

 

Everything You Need To Know About Logic Probes

July 29, 2017 by 43 Comments

We just spent the last hour watching a video, embedded below, that is the most comprehensive treasure trove of information regarding a subject that we should all know more about — sniffing logic signals. Sure, it’s a long video, but [Joel] of [OpenTechLab] leaves no stone unturned.

At the center of the video is the open-source sigrok logic capture and analyzer. It’s great because it supports a wide variety of dirt cheap hardware platforms, including the Salae logic and its clones. Logic is where it shines, but it’ll even log data from certain scopes, multimeters, power supplies, and more. Not only can sigrok decode raw voltages into bits, but it can interpret the bits as well using protocol decoder plugins written in Python. What this all means is that someday, it will decode everything. For free.

[Joel] knows a thing or two about sigrok because he started the incredibly slick PulseView GUI project for it, but that doesn’t stop him from walking you through the command-line interface, which is really useful for automated data capture and analysis, if that’s your sort of thing. Both are worth knowing.

But it’s actually the hardware details where this video shines. He breaks down all of the logic probes on his bench, points out their design pros and cons, and uses that basis to explain just what kind of performance you can expect for $20 or so. You’ll walk away with an in-depth understanding of the whole toolchain, from grabber probes to GUIs.
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Digitool Helps Debugging

July 11, 2017 by 9 Comments

Logic analyzers used to be large boxes full of high-speed logic and a display monitor. Today, they are more likely to be a small box with a USB port that feeds data to a PC application. [Juan Antonio Rubia Mena] wanted something more self-contained, so he built Digitool. Built around a PIC18F2525, the device can measure frequency up to 10 MHz and inject square waves up to 1 MHz into the circuit under test. Oh yeah. It also has a simple four-channel logic analyzer that displays on a tiny LCD.

The 500,000 sample per second rate and the 1024 sample buffer isn’t going to put any logic analyzer vendors out of business, but it is still enough to help you figure out why that SPI or I2C logic is messed up. It looks like a fun project that could have some usefulness.

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Logic Analyzer On Chips

May 17, 2017 by 9 Comments

The Internet is full of low-speed logic analyzer designs that use a CPU. There are also quite a few FPGA-based designs. Both have advantages and disadvantages. FPGAs are fast and can handle lots of data at once. But CPUs often have more memory and it is simpler to perform I/O back to, say, a host computer. [Mohammad] sidestepped the choice. He built a logic analyzer that resides partly on an FPGA and partly on an ARM processor.

In fact, his rationale was to replace built-in FPGA logic analyzers like Chipscope and SignalTap. These are made to coexist with your FPGA design, but [Mohammad] found they had limitations. They also eat up die space you might want for your own design, so by necessity, they probably don’t have much memory.

The system can capture and display 32-bit signals on a 640×480 VGA monitor in real-time. The system also has a USB mouse interface which is used to zoom and scroll the display. You can see a video of the thing in operation, below.

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