Bare-Metal STM32: Please Mind The Interrupt Event

March 26, 2021 by 27 Comments

Interruptions aren’t just a staple of our daily lives. They’re also crucial for making computer systems work as well as they do, as they allow for a system to immediately respond to an event. While on desktop computers these interrupts are less prominent than back when we still had to manually set the IRQ for a new piece of hardware using toggle switches on an ISA card, IRQs along with DMA (direct memory access) transfers are still what makes a system appear zippy to a user if used properly.

On microcontroller systems like the STM32, interrupts are even more important, as this is what allows an MCU to respond in hard real-time to an (external) event. Especially in something like an industrial process or in a modern car, there are many events that simply cannot be processed whenever the processor gets around to polling a register. Beyond this, interrupts along with interrupt handlers provide for a convenient way to respond to both external and internal events.

In this article we will take a look at what it takes to set up interrupt handlers on GPIO inputs, using a practical example involving a rotary incremental encoder.

Continue reading “Bare-Metal STM32: Please Mind The Interrupt Event” →

Hackaday Podcast 111: 3D Graphics Are Ultrasonic, Lobotomizing Alexa, 3D-Printing Leaky Rockets, And Gaming The Font System

March 26, 2021 by 4 Comments

Hackaday editors Mike Szczys and Elliot Williams curate a week of great hacks. Physical displays created in 3D space are a holy grail, and you can make one with 200 ultrasonic transducers, four FPGAs, and a lot math. Smart speakers have one heck of a microphone array in them, it’s yours for the hacking if you just roll your own firmware. Hobby servos can be awful, but this week we saw they can be made really great by cracking open the DC motor to add a simple DIY position sensor. And lasers are making their way into car headlights; we illuminate the situation in this episode.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (~60 MB)

Places to follow Hackaday podcasts:

Continue reading “Hackaday Podcast 111: 3D Graphics Are Ultrasonic, Lobotomizing Alexa, 3D-Printing Leaky Rockets, And Gaming The Font System” →

Serial Silicone Molding

March 26, 2021 by 5 Comments

The techniques for making single-digit quantities of custom molded parts don’t scale well when you need to make dozens, as [Kevin Holmes] discovered. He needed to make 80-some sets of a silicone motor mount, and the one-up mold process was not going to work. He explores several solutions, which he rejects as being too complicated. Finally [Kevin] comes up with the idea of daisy-chaining banks of molds clamped together with rails of stock metal bars. It’s a pretty nifty process to watch and you can check the video out below, which is not unlike a very slow 7495 four-bit shift register.

Even though the silicone he uses is clear, pay attention and you can still see the carry-out as it propagates from mold to mold. He manually performs the nibble carry operation from one bank to the next — we wonder if he could cascade these banks, and inject all 80 in one really big squeeze?

Why would someone need 80 sets of silicone rubber motor mounts, you may ask? Well, you may remember the 4-mation 3D zoetrope that we wrote about back in 2018. [Kevin] is one of the founders of this mesmerizing project, and it would seem that their Kickstarter project has been successful. As he demonstrates in the video below, without some type of noise dampening mounts, a rumble from the motor is amplified through the stage of the zoetrope. If you have any favorite mold-making tips for small batch manufacturing, let us know in the comments below. Thanks to [George Graves] for sending this tip our way.

Continue reading “Serial Silicone Molding” →

This Week In Security: XcodeSpy, Insecure SMS, And Partial Redactions

March 26, 2021 by 25 Comments

There seems to be a new trend in malware, targeting developers and their development and build processes. The appeal is obvious: rather than working to build and market a malicious application, an attacker just needs to infect a development machine. The hapless infected developers can now do the hard work to spread the malicious payload.

The newest example is XcodeSpy, discovered by a researcher who chose to remain anonymous. It works by using the Xcode IDE’s Run Script function to, well, run a script that completely backdoors your computer. The instance was found in a repackaged open source project, TabBarInteraction, but they’re just innocent victims. It was simple enough for someone to insert a script in the build process, and distribute the new, doped package. It’s probably not the only one out there, so watch out for Run Scripts with obfuscated payloads.

Continue reading “This Week In Security: XcodeSpy, Insecure SMS, And Partial Redactions” →

USB Comes To The ESP32

March 26, 2021 by 20 Comments

Since the ESP8266 came on the scene a few years ago and revolutionized the way microcontrollers communicate with other devices, incremental progress on this chip has occurred at a relatively even pace. First there was the realization that code could be run on the chip itself. Next the ESP32 was released which built more on that foundation. The next step in that process of improvement may be here now as well, with this project which turns the ESP32 into a USB host.

USB is not a native feature on all microcontrollers or even Arduino-compatible boards. While some do have it built in like those based on the 32u4 for example, most either don’t have it at all or rely on a separate on-board chip to do some form of translating. The ESP32 is lacking this advanced feature so the USB needs to be cobbled together from scratch if you want this specific board to be able to interface directly with peripherals. This project does just that, allowing for four USB 1.1 devices to be connected directly to the ESP32 without a separate dedicated chip.

If you’ve been waiting for USB on this tiny, capable microcontroller this might be your chance to try it out. All of the project’s code is available on the project page. And, while it is limited in scope, it’s easily able to handle a keyboard or mouse. This might be a more cost-effective way of doing something like a KVM switch rather than doing it with three Arduinos.

 

Undocumented X86 Instructions Allow Microcode Access

March 26, 2021 by 19 Comments

For an old CPU, finding all the valid instructions wasn’t very hard. You simply tried them all. Sure, really old CPUs might make it hard to tell what the instruction did, but once CPUs got illegal instruction traps, you could quickly just scan possible op codes and see what didn’t throw an exception. Modern processors, though, are quite another thing. For example, you might run a random instruction that locks up the machine or miss an instruction that would have been valid but the CPU is in the wrong mode. [Can Bölük] has a novel solution: By speculatively executing the target instruction and then monitoring the microcode sequencer, he can determine if the CPU is decoding an instruction even if it refuses to execute it.

Some unknown instructions may have power for good or evil, such as the recently announced undocumented instructions that can apparently rewrite the microcode. We expect to see a post soon on how to reprogram your Intel processor to run as a 6502 natively.

Continue reading “Undocumented X86 Instructions Allow Microcode Access” →

Data Blaster Is A Hip RPi Cyberdeck

March 25, 2021 by 16 Comments

Cyberdecks were once a science fiction approximation of what computing might look like in the future. In the end, consumer devices took a very different path. No matter, though, because the maker community decided cyberdecks were too awesome to ignore and started making their own. After lusting after some of the amazing builds already out there, [Zach Freedman] decided it was time to start his own build, resulting in the Data Blaster.

Epoxy holds the printed parts to the Pi 400

The Raspberry Pi has always been popular in the nascent cyberdeck scene, providing real Linux computing power in a compact, portable package. Now, we have the Raspberry Pi 400, which is exactly that, built into a shell that is, approximately, half of a cyberdeck. This formed the base of [Zach]’s build, coming in handy with its full-sized keyboard.

To that, he added a widescreen 1280×480 LCD, wearable display, and a USB powerbank, turning it into a true go-anywhere terminal. The 3D-printed handles are a particularly nice touch, making it easy to use the deck from a standing position, something that no laptop really does well. As a bonus, there’s even a tiny software defined radio on the side, complete with a collapsible antenna for that added cool factor. 

It’s a fun build, and a useful one too. We suspect the chunky plastics and grabbable design might actually make the Data Blaster preferable to a laptop in rugged field use versus a more traditional laptop. We’ve seen some other great work in this area, too. Video after the break.