AVR Reverse Engineering Hack Chat

April 19, 2021 by 10 Comments

Join us on Wednesday, April 21 at noon Pacific for the AVR Reverse Engineering Hack Chat with Uri Shaked!

We’ve all become familiar with the Arduino ecosystem by now, to the point where it’s almost trivially easy to whip up a quick project that implements almost every aspect of its functionality strictly in code. It’s incredibly useful, but we tend to lose sight of the fact that our Arduino sketches represent a virtual world where the IDE and a vast selection of libraries abstract away a lot of the complexity of what’s going on inside the AVR microcontroller.

While it’s certainly handy to have an environment that lets you stand up a system in a matter of minutes, it’s hardly the end of the story. There’s a lot to be gained by tapping into the power of assembly programming on the AVR, and learning how to read the datasheet and really run the thing. That was the focus of Uri Shaked’s recent well-received HackadayU course on AVR internals, and it’ll form the basis of this Hack Chat. Then again, since Uri is also leading a Raspberry Pi Pico and RP2040 course on HackadayU in a couple of weeks, we may end up talking about that too. Or we may end up chatting about something else entirely! It’s really hard to where this Hack Chat will go, given Uri’s breadth of interests and expertise, but we’re pretty sure of one thing: it won’t be boring. Make sure you log in and join the chat — where it goes is largely up to you.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, April 21 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.
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8-Bit Computer Addresses LEDs

April 19, 2021 by 2 Comments

Homebrew 8-bit computers tend to have fairly limited displays, often one or more seven-segment displays and an array of LEDs to show the values of RAM or perhaps some other states of the computer. [Duncan] is in the process of building just such an computer, but wondered if there was a way to create a more visually appealing display while still keeping the computer true to its 8-bit roots. With some interesting TTL logic he was able to create this addressable RGB LED display to some remarkable results.

The array works by controlling the WS2812B LED strips with a specific timing cycle which was pioneered by [Tim] for a different project. [Tim] was able to perform this timing cycle with some simple Assembly code, which means that [Duncan] could convert that code into TTL gate logic relatively easily. Using 74LS02 NOR chips gets the job done as far as timing goes, and the pulses are then fed into a shift register and support logic which then creates the signal for the LED strips.

When everything is said and done, [Duncan] has a fully addressable 16×16 RGB LED array as a display for his 8-bit computer without violating any of his design principles and keeping everything to discrete TTL logic chips and a stick of RAM. It’s a unique method of display that might go along really well with any other homebrew computer like this one that’s also built with 74LS chips.

Space Propulsion: Separating Fact From Science Fiction

April 19, 2021 by 102 Comments

An unfortunate property of science-fiction is that it is, tragically, fiction. Instead of soaring between the stars and countless galaxies out there, we find ourselves hitherto confined to this planet we call Earth. Only a handful of human beings have ever made it as far as the Earth’s solitary moon, and just two of our unmanned probes have made it out of the Earth’s solar system after many decades of travel. It’s enough to make one despair that we’ll never get anywhere near the fantastic future that was seemingly promised to us by science-fiction.

Yet perhaps not all hope is lost. Over the past decades, we have improved our chemical rockets, are experimenting with various types of nuclear rockets, and ion thrusters are a common feature on modern satellites as well as for missions within the solar system. And even if the hype around the EMDrive vanished as quickly as it had appeared, the Alcubierre faster-than-light drive is still a tantalizing possibility after many years of refinements.

Even as physics conspires against our desire for a life among the stars, what do our current chances look like? Let’s have a look at the propulsion methods which we have today, and what we can look forward to with varying degrees of certainty.

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Power Supply Uses Thin Form Factor

April 19, 2021 by 8 Comments

We’ve seen lots of power supply projects that start with an ATX PC power supply. Why not? They are cheap and readily available. Generally, they perform well and have a good deal of possible output. [Maco2229’s] design, though, looks a lot different. First, it is in a handsome 3D-printed enclosure. But besides that, it uses a TFX power supply — the kind of supply made for very small PCs as you’d find in a point of sale terminal or a set-top box.

Like normal PC supplies, these are inexpensive and plentiful. Unlike a regular supply, though, they are long and skinny. A typical supply will be about 85x65x175mm, although the depth (175mm) will often be a little shorter. Compare this to a standard ATX supply at  150x86x140mm, although many are shorter in depth. Volume-wise, that’s nearly 967 cubic centimeters versus over 1,800. That allows the project to be more compact than a similar one based on ATX.

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PiStorm Brings Modern Muscle To The Amiga

April 19, 2021 by 40 Comments

The Amiga, well known as the best and greatest computer ever designed, is nonetheless a platform of yesteryear. Its 68K, and later PowerPC, architectures have both been abandoned by the mainstream, and its attractive grey industrial design no longer graces store shelves. That doesn’t mean the platform is dead however, with diehard shredders like [Claude Schwarz] working hard to keep it alive with projects like PiStorm.

PiStorm is a Motorola 68K CPU emulator, running on a Raspberry PI 3A. The Pi uses its GPIOs to interact with a CPLD chip, which acts as the logic glue to allow the modern single board computer to emulate the Amiga’s original processor. However, it’s more than just an easy way to replace or upgrade a CPU. It also offers additional features, like retargetable graphics acceleration, SCSI disk emulation, and the ability to run whatever Kickstart ROM you so desire.

While the initial work has been done on a Pi 3A, [Claude] has also demonstrated some of the basic functionality running on a Pi CM4 too. The benchmarks are more fierce than a Beyoncé Super Bowl half time show, so if you need grunt on your classic Amiga, this could be the way to go. As a bonus, files to build your own are readily available on Github, which should make it a mite more accessible than other Amiga accelerator boards.

We wonder whether this accelerator could be used to hook the Amiga up to Spotify, a la this previous build. Likely, time will tell. Video after the break.

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DIY Wireless Serial Adapter Speaks (True) RS-232

April 18, 2021 by 80 Comments

There is a gotcha lurking in wait for hackers who look at a piece of equipment, see a port labeled “Serial / RS-232”, and start to get ideas. The issue is the fact that the older the equipment, the more likely it is to be a bit old-fashioned about how it expects to speak RS-232. Vintage electronics may expect the serial data to be at bipolar voltage levels that are higher than what the typical microcontroller is used to slinging, and that was the situation [g3gg0] faced with some vintage benchtop equipment. Rather than deal with cables and wired adapters, [g3gg0] decided to design a wireless adapter with WiFi and Bluetooth on one end, and true RS-232 on the other.

The adapter features an ESP32 and is attached to a DB-9 plug, so it’s nice and small. It uses the ST3232 chip to communicate at 3 V logic levels on the microcontroller side, supports bipolar logic up to +/-13 V on the vintage hardware side, and a rudimentary web interface allows setting hardware parameters like baud rate. The nice thing about the ST3232 transceiver is that it is not only small, but can work from a 3 V supply with only four 0.1 uF capacitors needed for the internal charge pumps.

As for actually using the adapter, [g3gg0] says that the adapter’s serial port is exposed over TCP on port 23 (Telnet) which is supported by some programs and hardware. Alternately, one can connect an ESP32 to one’s computer over USB, and run firmware that bridges any serial data directly to the adapter on the other end.

Design files including schematic, bill of materials, and PCB design are shared online, and you can see a brief tour of the adapter in the video, embedded below.

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Exploring Op Amp Loading

April 18, 2021 by 13 Comments

Op amps are generally pretty easy to apply, but there are some practical nonideal behaviors you have to keep in mind. [EEforEveryone] takes a test board with some 2X amplifiers on it and — after some fiddling around with the scope probes — demonstrates the effect of capacitive loading on the output of an op amp. (Video, embedded below.)

The op amp in question is the OP07. In fact, there are two identical opamps looking at the single input. The output of one op amp feeds directly to the scope probes. The second one passes through a bipolar transistor buffer consisting of an NPN and PNP transistor. Both outputs have optional capacitors that can be jumpered in or out of the circuit.

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