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238 Articles

Run Your Favorite 8-bit Games On An ESP32

June 9, 2020 by 20 Comments

Here at Hackaday HQ we’re no strangers to vintage game emulation. New versions of old consoles and arcade cabinets frequently make excellent fodder for clever hacks to cram as much functionality as possible into tiny modern microcontrollers. We’ve covered [rossumur]’s hacks before, but the ESP_8-bit is a milestone in comprehensive capability. This time, he’s topped himself.

There isn’t much the ESP 8-bit won’t do. It can emulate three popular consoles, complete with ROM selection menus (with menu bloops). Don’t worry about building a controller, just connect any old (HID compliant) Bluetooth Classic keyboard or WiiMote you have at hand. Or if that doesn’t do it, a selection of IR devices ranging from joysticks from the Atari Flashback 4 to Apple TV remotes are compatible. Connect analog audio and composite video and the device is ready to go.

The system provides this impressive capability with an absolute minimum of components. Often a schematic is too complex to fit into a short post, but we’ll reproduce this one here to give you a sense for what we’re talking about. Come back when you’ve refreshed your Art of Electronics and have a complete understanding of the hardware at work. We never cease to be amazed at the amount of capability available in modern “hobbyist” components. With such a short BOM this thing can be put together by anyone with an ESP-32-anything.

There’s one more hack worth noting; the clever way [rossumur] gets full color NTSC composite video from a very busy microcontroller. They note that NTSC can be finicky and requires an extremely stable high speed reference clock as a foundation. [rossumur] discovered that the ESP-32 includes a PLL designed for audio work (the “APLL”) which conveniently supports fractional components, allowing it to be trimmed to within an inch of the desired frequency. The full description is included in the GitHub page for the project and includes detailed background of various efforts to get color NTSC video (including the names of a couple hackers you might recognize from these pages).

Continue reading “Run Your Favorite 8-bit Games On An ESP32” →

A Pulse Oximeter From Very Little

May 16, 2020 by 31 Comments

Against the backdrop of a global respiratory virus pandemic, it’s likely that more than a few readers have been thinking about pulse oximeters. You may even have looked at one closely and seen that it’s little more than a device which shines light through your finger, and wondered how they work. It’s something [Giulio Pons] has done, and to show us how it’s done he’s created a working pulse oximeter of his own.

He started with an infra-red heartbeat sensor module, which is revealed as nothing more than an IR LED and a photodiode. Sampling the output from the photodiode allows measurement of heartbeat, but gives not clue as to oxygen saturation. The interesting part comes via the property of red light in that it’s transmission through flesh varies with oxygen saturation, so adding a red LED and alternately measuring from the IR and red illuminations allows a saturation figure to be derived.

Commercial pulse oximeters are pretty cheap, so many of us will no doubt simply order one from the usual sources and call it good. But it’s always interesting to know how any device works, and this project reveals something simpler than we might have expected. If pulse oximeters interest you, compare it with this one we featured a few years ago.

Any Remote Can Be A Universal Remote

May 1, 2020 by 23 Comments

Everyone has a stack of old infra-red remote controllers lying around, for devices that have long since shuffled off this mortal coil. Containing little more than an application-specific encoder chip, keyboard, and IR LED, they’re of little use unless you happen to have another device that uses the same encoding scheme. For [RiYa] though they represent an opportunity, to be repurposed into controllers for other devices. How? Hijack the bitstream with an ATtiny13 microcontroller, re-encode it, and send it out afresh into the ether from the LED. It’s a gloriously simple solution which we can’t help applauding, and has the potential to cheaply replace all those universal remotes.

The ATtiny itself along with a buffer to drive the LED is mounted on a small breakout board and concealed within the shell of the remote. We don’t learn much about the power supply arrangement, but we’d expect the ATtiny to be on its most power-sipping behaviour as anything which would shorten the battery life of a remote would be unlikely to be popular with a couch potato forced to change AA cells every few weeks. There’s a plan for a learning mode to make it more like a commercial universal remote, but for now the translation is hard coded.

Of course, should you lack a handy old remote to play with, you can always try a smartphone.

The Nintendo Game Boy Color Is An Aircon Remote

April 29, 2020 by 5 Comments

Those of you who are familiar with 1990s handheld consoles may recall that Nintendo’s Game Boy Color had an infra-red receiver and transmitter. The thought of a handheld computer with infra-red capabilities interested [jg], who immediately set about converting it into a remote control for an air conditioner.

The Game Boy doesn’t have dedicated infra-red remote control hardware, instead the IR diodes appear to be connected to I/O lines. Thus the bitstream bas to be bit-banged, and takes the processor’s entire attention when transmitting. The software is neatly placed on a reprogrammed bootleg cartridge.

It’s an interesting read in terms of the approach to reverse engineering, for example finding the parameters of 37 kHz infra-red remote control by trial and error rather than by a quick read up on the subject, or searching for information on National air conditioners and finding nothing, but not searching the National brand itself to find that a search on Panasonic air conditioners would likely give all the information needed. But the end result operates the appliance, so it’s good to record a success.

This isn’t the first time we’ve seen a Game Boy control something, though we can’t recall seeing another using the IR. Need a brilliant overview of the Game Boy?  We’ve got you covered.

Thanks [Roel] for the tip.

Header image: Evan-Amos / Public domain.

Teardown Of Oddball Night Vision Shows Off Retro-futuristic Vibe

April 8, 2020 by 14 Comments

Night vision aficionado [Nicholas C] shared an interesting teardown of a Norwegian SIMRAD GN1 night vision device, and posted plenty of pictures, along with all kinds of background information about their construction, use, and mounting. [Nicholas] had been looking for a night vision device of this design for some time, and his delight in finding one is matched only by the number of pictures and detail he goes into when opening it up.

The GN1 rocks an irresistible retro-futuristic look.

What makes the SIMRAD GN1 an oddball is the fact that it doesn’t look very much like other, better known American night vision devices. Those tend to have more in common with binoculars than with the GN1’s “handheld camera” form factor. The GN1 has two eyepieces in the back and a single objective lens on the front, which is off-center and high up. The result is a seriously retrofuturistic look, which [Nicholas] can’t help but play to when showing off some photos.

[Nicholas] talks a lot about the build and tears it completely down to show off the internal optical layout necessary to pipe incoming light through the image intensifier and bend it around to both eyes. As is typical for military hardware like this, it has rugged design and every part has its function. (A tip: [Nicholas] sometimes refers to “blems”. A blem is short for blemish and refers to minor spots on optics that lead to visual imperfections without affecting function. Blemished optics and intensifier tubes are cheaper to obtain and more common on the secondary market.)

In wrapping up, [Nicholas] talks a bit about how a device like this is compatible with using sights on a firearm. In short, it’s difficult at best because there’s a clunky thing in between one’s eyeballs and the firearm’s sights, but it’s made somewhat easier by the fact that the GN1 can be mounted upside down without affecting how it works.

Night vision in general is pretty cool stuff and of course DIY projects abound, like the OpenScope project which leverages digital cameras and 3D printing, as well as doing it the high-voltage image intensifier tube way.

3D Printed Flip Clock Is Worth A Second Look

February 12, 2020 by 12 Comments

Flip clocks: they were cool long before Bill Murray was slapping one repeatedly in Groundhog Day, they were cool in 1993, and they’re still cool now. If you can’t find one on the secondhand market, you’re in luck, because [iz2k] has laid out an extensive blueprint for building a gorgeous retro-looking clock with some modern touches.

There’s a Raspberry Pi to fetch the time, the weather, and the Spotify. Old flip clocks invariably tuned in FM radio, so [iz2k] used an RTL-SDR dongle and a software decoder for the deed. This clock even has a big snooze bar, which functions like a night light when there is no alarm actively going off. The three groups of painstakingly-printed flaps are controlled with stepper motors and an IR transmitter/receiver pair to do the counting.

For the interface, [iz2k] kept things nice and simple. The big-knobbed rotary encoder handles volume up/down/mute, and the little one on the front switches between FM radio, Spotify, and silence. Moving either knob generates feedback by flashing LEDs that sit underneath the display. Take a few seconds to flip past the break and check out the short demo.

If you do find a nice flip clock out in the wild, maybe you can retrofit it.

Continue reading “3D Printed Flip Clock Is Worth A Second Look” →

See In The Dark, The Simple Way

February 9, 2020 by 42 Comments

Night vision googles used to be the exclusive preserve of the military, and then of the well-heeled. Image intensifier tubes were very expensive, and needed high-voltage power supplies to keep them going. Now that we have solid-state infra-red cameras the task of seeing in the dark had become much simpler, and [Alex Zidros] is here to show us just how easy that can be. His night vision goggles take a selection of off-the-shelf parts and a little bit of 3D printing to produce a complete set-up for a fraction of the cost of those night-vision goggles of old.

At its heart is a little NTSC/PAL LCD display in a 3D printed bracket. These used to be a small display of choice, but we see them rarely now because standalone displays and the microcontrollers to drive them have become so much more useful. Driving the display is a video camera with its IR filter removed, and providing illumination is an IR flashlight. In effect it’s a classic analogue CCTV system in miniature, but the most important thing is that it works.

We might have expected a Raspberry Pi Zero and NoIR camera, but it’s difficult to argue with a functioning night vision system. If you want to look at a project with an image intensifier tube though, we’ve covered one of those in the past.