Pi Pico Turns Atari 2600 Into A Lo-fi Photo Frame

March 27, 2025 by Jenny List 7 Comments

The cartridge based game consoles of decades ago had a relatively simple modus operandi — they would run a program stored in a ROM in the cartridge, and on the screen would be the game for the enjoyment of the owner. This made them simple in hardware terms, but for hackers in the 2020s, somewhat inflexible. The Atari 2600 is particularly troublesome in this respect, with its clever use of limited hardware making it not the easiest to program at the best of times. This makes [Nick Bild]’s Atari 2600 photo frame project particularly impressive.

The 2600 has such limited graphics hardware that there’s no handy frame buffer to place image data into, instead there are some clever tricks evolved over years by the community to build up bitmap images using sprites. Only 64 by 84 pixels are possible, but for mid-70s consumer hardware this is quite the achievement.

In the case of this cartridge the ROM is replaced by a Raspberry Pi Pico, which does the job of both supplying the small Atari 2600 program to display the images, and feeding the image data in a form pre-processed for the Atari.

The result is very 8-bit in its aesthetic and barely what you might refer to as photos at all, but on the other hand making the Atari do this at all is something of a feat. Everything can be found in a GitHub repository.

If new hardware making an old console perform unexpected tricks is your bag, we definitely have more for you.

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Metal Detector Built With Smartphone Interface

March 25, 2025 by Zoe Skyforest 8 Comments

If you think of a metal detector, you’re probably thinking of a fairly simple device with a big coil and a piercing whine coming from a tinny speaker. [mircemk] has built a more modern adaptation. It’s a metal detector you can use with your smartphone instead.

The metal detector part of the project is fairly straightforward as far as these things go. It uses the pulse induction technique, where short pulses are fired through a coil to generate a magnetic field. Once the pulse ends, the coil is used to detect the decaying field as it spreads out. The field normally fades away in a set period of time. However, if there is metal in the vicinity, the time to decay changes, and by measuring this, it’s possible to detect the presence of metal.

In this build, an ESP32 is in charge of the show, generating the necessary pulses and detecting the resulting field. It’s paired with the usual support circuitry—an op-amp and a few transistors to drive the coil appropriately, and the usual smattering of passives. The ESP32 then picks up the signal from the coil and processes it, passing the results to a smartphone via Bluetooth.

The build is actually based on a design by [Neco Desarrollo], who presents more background and other variants for the curious. We’ve featured plenty of [mircemk]’s projects before, like this neat proximity sensor build. Continue reading “Metal Detector Built With Smartphone Interface” →

Three SPI Busses Are One Too Many On This Cheap Yellow Display

March 20, 2025 by Jenny List 25 Comments

The Cheap Yellow Display may not be the fastest of ESP32 boards with its older model chip and 4 MB of memory, but its low price and useful array of on-board peripherals has made it something of a hit in our community. Getting the most out of the hardware still presents some pitfalls though, as [Mark Stevens] found out when using one for an environmental data logger. The problem was that display, touch sensor, and SD card had different SPI busses, of which the software would only recognise two. His solution involves a simple hardware mod, which may benefit many others doing similar work.

It’s simple enough, put the LCD and SD card on the same bus, retaining their individual chip select lines. There’s a track to be cut and a bit of wiring to be done, but nothing that should tax most readers too much. We’re pleased to see more work being done with this board, as it remains a promising platform, and any further advancements for it are a good thing. If you’re interested in giving it a go, then we’ve got some inspiration for you.

World’s Smallest Blinky, Now Even Smaller

March 19, 2025 by Dan Maloney 29 Comments

Here at Hackaday, it’s a pretty safe bet that putting “World’s smallest” in the title of an article will instantly attract comments claiming that someone else built a far smaller version of the same thing. But that’s OK, because if there’s something smaller than this nearly microscopic LED blinky build, we definitely want to know about it.

The reason behind [Mike Roller]’s build is simple: he wanted to build something smaller than the previous smallest blinky. The 3.2-mm x 2.5-mm footprint of that effort is a tough act to follow, but technology has advanced somewhat in the last seven years, and [Mike] took advantage of that by basing his design on an ATtiny20 microcontroller in a WLCSP package and an 0201 LED, along with a current-limiting resistor and a decoupling capacitor. Powering the project is a 220-μF tantalum capacitor, which at a relatively whopping 3.2 mm x 1.6 mm determines the size of the PCB, which [Mike] insisted on using.

Assembling the project was challenging, to say the least. [Mike] originally tried a laboratory hot plate to reflow the board, but when the magnetic stirrer played havoc with the parts, he switched to a hot-air rework station with a very low airflow. Programming the microcontroller almost seemed like it was more of a challenge; when the pogo pins he was planning to use proved too large for the job he tacked leads made from 38-gauge magnet wire to the board with the aid of a micro hot air tool.

After building version one, [Mike] realized that even smaller components were available, so there’s now a 2.4 mm x 1.5 mm version using an 01005 LED. We suspect there’ll be a version 3.0 soon, though — he mentions that the new TI ultra-small microcontrollers weren’t available yet when he pulled this off, and no doubt he’ll want to take a stab at this again.

Speeding Up Your Projects With Direct Memory Access

March 18, 2025 by Zoe Skyforest 37 Comments

Here’s the thing about coding. When you’re working on embedded projects, it’s quite easy to run into hardware limitations, and quite suddenly, too. You find yourself desperately trying to find a way to speed things up, only… there are no clock cycles to spare. It’s at this point that you might reach for the magic of direct memory access (DMA). [Larry] is here to advocate for its use.

DMA isn’t just for the embedded world; it was once a big deal on computers, too. It’s just rarer these days due to security concerns and all that. Whichever platform you’re on, though, it’s a valuable tool to have in your arsenal. As [Larry] explains, DMA is a great way to move data from memory location to memory location, or from memory to peripherals and back, without involving the CPU. Basically, a special subsystem handles trucking data from A to B while the CPU gets on with whatever other calculations it had to do. It’s often a little more complicated in practice, but that’s what [Larry] takes pleasure in explaining.

Indeed, back before I was a Hackaday writer, I was no stranger to DMA techniques myself—and I got my project published here! I put it to good use in speeding up an LCD library for the Arduino Due. It was the perfect application for DMA—my main code could handle updating the graphics buffer as needed, while the DMA subsystem handled trucking the buffer out to the LCD quicksmart.

If you’re struggling with updating a screen or LED strings, or you need to do something fancy with sound, DMA might just be the ticket. Meanwhile, if you’ve got your own speedy DMA tricks up your sleeve, don’t hesitate to let us know!

Checking In On The ISA Wars And Its Impact On CPU Architectures

March 18, 2025 by Maya Posch 33 Comments

An Instruction Set Architecture (ISA) defines the software interface through which for example a central processor unit (CPU) is controlled. Unlike early computer systems which didn’t define a standard ISA as such, over time the compatibility and portability benefits of having a standard ISA became obvious. But of course the best part about standards is that there are so many of them, and thus every CPU manufacturer came up with their own.

Throughout the 1980s and 1990s, the number of mainstream ISAs dropped sharply as the computer industry coalesced around a few major ones in each type of application. Intel’s x86 won out on desktop and smaller servers while ARM proclaimed victory in low-power and portable devices, and for Big Iron you always had IBM’s Power ISA. Since we last covered the ISA Wars in 2019, quite a lot of things have changed, including Apple shifting its desktop systems to ARM from x86 with Apple Silicon and finally MIPS experiencing an afterlife in the form of LoongArch.

Meanwhile, six years after the aforementioned ISA Wars article in which newcomer RISC-V was covered, this ISA seems to have not made the splash some had expected. This raises questions about what we can expect from RISC-V and other ISAs in the future, as well as how relevant having different ISAs is when it comes to aspects like CPU performance and their microarchitecture.

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Ask Hackaday: What Would You Do With The World’s Smallest Microcontroller?

March 17, 2025 by Dan Maloney 94 Comments

It’s generally pretty easy to spot a microcontroller on a PCB. There are clues aplenty: the more-or-less central location, the nearby crystal oscillator, the maze of supporting passives, and perhaps even an obvious flash chip lurking about. The dead giveaway, though, is all those traces leading to the chip, betraying its primacy in the circuit. As all roads lead to Rome, so it often is with microcontrollers.

It looks like that may be about to change, though, based on Texas Instruments’ recent announcement of a line of incredibly small Arm-based microcontrollers. The video below shows off just how small the MSPM0 line can be, ranging from a relatively gigantic TSSOP-20 case down to an eight-pin BGA package that measures only 1.6 mm by 0.86 mm. That’s essentially the size of an 0603 SMD resistor, a tiny footprint for a 24-MHz Cortex M0+ MCU with 16-kB of flash, 1-kB of SRAM, and a 12-bit ADC. The larger packages obviously have more GPIO brought out to pins, but even the eight-pin versions support six IO lines.

Of course, it’s hard not to write about a specific product without sounding like you’re shilling for the company, but being first to market with an MCU in this size range is certainly newsworthy. We’re sure other manufacturers will follow suit soon enough, but for now, we want to know how you would go about using a microcontroller the size of a resistor. The promo video hints at TI’s target market for these or compact wearables by showing them used in earbuds, but we suspect the Hackaday community will come up with all sorts of creative and fun ways to put these to use — shoutout to [mitxela], whose habit of building impossibly small electronic jewelry might be a good use case for something like this.

There may even be some nefarious use cases for a microcontroller this small. We were skeptical of the story about “spy chips” on PC motherboards, but a microcontroller that can pass for an SMD resistor might change that equation a bit. There’s also the concept of “Oreo construction” that these chips might make a lot easier. A board with a microcontroller embedded within it could be a real security risk, but on the other hand, it could make for some very interesting applications.

What’s your take on this? Can you think of applications where something this small is enabling? Or are microcontrollers that are likely to join the dust motes at the back of your bench after a poorly timed sneeze a bridge too far? Sound off in the comments below.

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