Break Your Scope’s Bandwidth Barrier

January 24, 2019 by Al Williams 12 Comments

Oscilloscope bandwidth is a tricky thing. A 100 MHz scope will have a defined attenuation (70%) of a 100 MHz sine wave. That’s not really the whole picture, though, because we aren’t always measuring sine waves. A 100 MHz square wave, for example, will have sine wave components at 100 MHz, 300 MHz, and the other odd harmonics. However, it isn’t that a 100 MHz scope won’t show you something at a higher frequency — it just doesn’t get the y-axis right. [Daniel Bogdanoff] from Keysight decided to think outside of the box and made a video about using scopes beyond their bandwidth specification. You can see that video, below.

[Daniel] calls this a “spec hacks” but they aren’t really hacks to the scope. They are just methods that don’t care about the scope’s rated bandwidth. In this particular spec hack, he shows how the frequency counter using a 70 MHz scope’s trigger circuit can actually read up to 410 MHz. A 100 MHz scope was able to read almost 530 MHz.

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Cool Tools: A Little Filesystem That Keeps Your Bits On Lock

January 24, 2019 by Kerry Scharfglass 52 Comments

Filesystems for computers are not the best bet for embedded systems. Even those who know this fragment of truth still fall into the trap and pay for it later on while surrounded by the rubble that once was a functioning project. Here’s how it happens.

The project starts small, with modest storage needs. It’s just a temperature logger and you want to store that data, so you stick on a little EEPROM. That works pretty well! But you need to store a little more data so the EEPROM gets paired with a small blob of NOR flash which is much larger but still pretty easy to work with. Device settings go to EEPROM, data logs go to NOR. That works for a time but then you remember that people on the Internet are all about the Internet of Things so it’s time to add WiFi. You start serving a few static pages with that surprisingly capable processor and bump into storage problems again so the NOR flash gets replaced with an SD card and now the logs go there too. Suddenly you’re dealing with multiple files and want access on a computer so a real filesystem is in order. FAT is easy, so the card grows a FAT filesystem. Everything is great, but you start to notice patches missing from the logs. Then the SD card gets totally corrupted. What’s going on? Let’s take a look at the problem, and how to reach embedded file nirvana.

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The Mac That Helped Build The Xbox Rides Again

January 24, 2019 by Tom Nardi 11 Comments

The original Xbox, released in 2001 by Microsoft, was notable for being built out of largely off-the-shelf PC components. With a custom Pentium III CPU and IDE peripherals, the console was much closer to a contemporary desktop computer than any of the dedicated game consoles which had come before it. Which of course makes perfect sense if you think about it. Microsoft would want to use technology they were intimately acquainted with on their first foray into gaming market, and if there’s anything Microsoft knows better than forced system updates, it’s x86 computers.

But for their follow-up system, the Xbox 360, Microsoft decided to go with a PowerPC processor they co-developed with IBM. Naturally this meant they needed PowerPC development systems to give to developers, which is how Microsoft ended up briefly distributing PowerMac G5’s. [Pierre Dandumont] came into possession of one of these oddball Microsoft-branded Macs, though unfortunately the hard drive had been wiped. But with the help of a leaked drive image and some hardware sleuthing, he’s now got the machine up and running just like it was when Microsoft was sending them to developers between 2003 and 2005.

Since you’re reading this on Hackaday, you might have guessed there was a little more to the story then just downloading an ISO and writing it to the hard drive of a PowerMac G5. There’s apparently some debate in the community about whether or not it’s some form of rudimentary DRM on Microsoft’s part, but in any event, the development kit operating system will only run on a G5 with very specific hardware. So the challenge is not only figuring out what hardware the software is looking for, but finding it and getting it installed over a decade after its prime.

Most of the required hardware, like the Intel 741462-010 network card or 160 GB Seagate ST3160023AS hard drive were easy enough to track down on eBay. But the tricky one was finding a Mac version of the ATi Radeon X800 XT. [Pierre] ended up getting a much more common ATi FireGL X3 and flashing it with the Mac X800 firmware. This is a little easier said than done as depending on which manufacturer made the memory on your specific video card you have to fiddle with the clock speeds to get a usable image, but in the end he found the winning combination and the development kit OS booted up with his hacked graphics card.

So what does all this get you in 2019? [Pierre] admits nothing terribly useful, but it’s still pretty cool. The system lets you run Xbox and Xbox 360 binaries, and even features the old Xbox 360 “blade” style dashboard. He says that he’s only had limited success getting retail games to actually run on the thing, but if your goal was running Xbox 360 games in 2019 there’s certainly better ways to do that anyway. Like, buying an Xbox 360.

We’ve previously talked about the Xbox 360’s rather unusual processor, but around these parts we more often see projects which involve tearing Microsoft’s sophomore console apart than digging into how it actually worked.

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Running OpenCL On A Raspberry Pi GPU

January 24, 2019 by Richard Baguley 30 Comments

This is an interesting development for media users and machine learning hackers: [doe300] has implemented OpenCL on the Raspberry Pi 3 Model B+called VCFCL That’s big news because the Pi 3+ has a Graphics Processing Unit (GPU) built into the processor that has been generally underutilized. The VideoCore IV GPU is built into the Broadcom BCM2837B0 and is surprisingly capable for a low-power chip. Although this GPU is well documented, it hasn’t been used that widely because you have to code specifically for this class of GPU. Adding in support for a high-level framework like OpenCL will make it much easier to run and adapt existing packages.

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