Driving A PAL TV Over RF Thanks To PWM Harmonics

While most analog televisions come with composite video inputs on a yellow RCA jack, the feature is not universal. This problem was even more prevalent in the 1980s, and most home consoles got around the problem by instead feeding video to the television’s tuner with an RF modulator. [Manzel Seet] had just such a television which used the PAL standard. Wanting to display images from a microcontroller, he put together PAL-Streamer.

The aim of the project was to display images on an analog television with minimal investment in hardware over and above what [Manzel] already had on hand. To this end, the project was built using a STM32F411 Nucleo development board. Capable of running at clock speeds up to 100 MHz, there’s plenty of grunt to handle demanding tasks like outputting video signals to a TV.

To achieve the target frequency of VHF Channel 3 (61.25 MHz), [Manzel] elected to rely on the onboard PWM hardware, after being inspired by [CNLohr]’s ATTiny NTSC project. The project takes advantage of the odd harmonics of square waves. Setting the PWM output to operate at 6.86 MHz, the ninth harmonic ends up at around 61.71 MHz, close enough to be tuned in on the TV set. With the hard part done, [Manzel] then implemented a virtual COM port allowing an attached PC to send PNG images or GIF animations to the display.

It’s a fun project that shows it’s possible to drive all kinds of analog displays if you’re willing to be creative about how you do it. Files are available on GitHub for those eager to recreate the work. [Manzel] points out that this method does put out a lot of RF energy in the surrounding bands, but for direct hookup to an antenna input, it works just fine. We love to see creative video projects on microcontrollers, so if you’ve figured out how to get an Arduino Uno to do 1080P over HDMI, be sure to let us know. Video after the break.

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A Homebrew Radio, As All The Best Homebrew Radios Should Be

It started with an old TV sound chip, and some curiosity. The TDA1701 that [Philip Bragg] found in a box of junk is a complete FM IF strip and audio power amplifier from the golden age of analogue PAL televisions, and while it was designed for the 5.5 MHz or 6 MHz FM subcarrier of European broadcast TV, he found it worked rather well at the more usual 10.7 MHz of a radio receiver. There followed a long thread detailing the genesis bit-by-bit of a decent quality VHF radio receiver, built dead-bug-style on a piece of PCB material.

The TDA1701 was soon joined by a couple of stages of IF amplification with a ceramic filter, and then by several iterations of a JFET mixer. A varicap tuned MOSFET RF amplifier followed, and then a local oscillator. Finally it became a fully-functional FM radio, with probably far better performance than most commercial radios. He admits tuning is a little impractical though, with what appears to be a cermet preset potentiometer covering the entire band.

We suspect this project isn’t finished, and we hope he posts the schematic. But it doesn’t really matter if he doesn’t, because the value here isn’t in the design. Instead it lies in the joy of creating an ad-hoc radio just for the fun of it, and that’s something we completely understand.

We’ve covered a lot of radios in our time, and while it might be the first to feature a TV sound chip, it’s not the first built on bare PCB.

Grey Gear: French TV Encryption, 1980s Style

Who among us didn’t spend some portion of their youth trying in vain to watch a scrambled premium cable TV channel or two? It’s a wonder we didn’t blow out our cones and rods watching those weird colors and wavy lines dance across the screen like a fever dream.

In the early days of national premium television in America, anyone who’d forked over the cash and erected a six-foot satellite dish in the backyard could tune in channels like HBO, Showtime, and the first 24-hour news network, CNN. Fed up with freeloaders, these channels banded together to encrypt their transmissions and force people to buy expensive de-scrambling boxes. On top of that, subscribers had to pay a monthly pittance to keep the de-scrambler working. Continue reading “Grey Gear: French TV Encryption, 1980s Style”

Run Your Favorite 8-bit Games On An ESP32

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).

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Bitluni Brings All The ESP-32 Multimedia Hacks To Supercon

Of all the people I was looking forward to meeting at Supercon, aside from my Hackaday colleagues with whom I had worked for five years without ever meeting, was a fellow from Germany named Matthias Balwierz. The name might not ring a bell, but he’ll certainly be familiar to Hackaday readers as Bitluni, the sometimes goofy but always entertaining and enlightening face of “Bitluni’s Lab” on YouTube.

I’d been covering Bitluni’s many ESP32 hacks over the years, and had struck up a correspondence with him, swapping ideas and asking for advice on the many projects I start but somehow never finish. Luckily for us, Bitluni is far better on follow-through than I am, and he brought that breadth and depth of experience to the Design Lab stage for that venue’s last talk of the 2019 Superconference, before the party moved next door for the badge-hacking presentations.

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10-Way Game Console Lets Everyone Play

[Bitluni]’s motto seems to be, “When you’re busy, get busier.” At least that would explain adding even more work to his plate in the run-up to the Hanover Maker Faire and coming up with a ten-player game console from scratch.

As for this being extra work, recall that [bitluni] had already committed to building a giant ping pong ball LED wall for the gathering. That consisted of prototyping a quarter-scale panel, building custom tooling to get him past the literal pain point of punching 1200 holes, and wiring, programming and testing the whole display. Building a game console that supports ten players at once seems almost tame by comparison. The console is built around an ESP32 module, either WROOM or WROVER thanks to a clever multifunctional pad layout on the slick-looking white PCBs. [bitluni] went with a composite video output using the fast R-2R ladder network DAC that he used for his ESP32 VGA project. The console supports ten Nintendo gamepads for a simple but engaging game something like the Tron light cycles. Unsurprisingly, players found it more fun to just crash into each other on purpose.

Sure, it could have been biting off more than he could chew, but [bitluni] delivered and we appreciate the results. There’s something to be said for adding a little pressure to the creative process.

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This Commodore 16 Is An NTSC One… No, Wait, It’s A PAL One!

We’re used to our computers being powerful enough in both peripheral and processing terms to be almost infinitely configurable under the control of software, but there was a time when that was not the case. The 8-bit generation of home computers were working towards the limits of their capability just to place an image on a TV screen, and every component would have been set up to do just the job it was intended for. Thus when different countries had different TV standards such as the mostly-European PAL and the mostly-American NTSC, there would have been different models of the same machine for each market. The Commodore 16 was just such a machine, and [Adrian Black] has modified his NTSC model with a custom ROM, an Arduino and an Si5351 clock generator to be switchable between the two.

The differences between a PAL and NTSC C16 are two-fold. The clock for the video chip is of a different frequency, and the ROM contents differ too. [Adrian]’s machine therefore has a larger ROM containing both versions which are switchable via one of the upper address lines. A couple of tracks cut in the crystal oscillator circuit allow him to inject a new clock from the Si5351 module, and and Arduino controls everything. The appropriate ROM and clock are selected via a very simple interface, the reset button is captured and while a short press still resets the computer a long one switches the mode.

Despite having its principal engineer, [Bil Herd] as a colleague here at Hackaday, it’s sad that we don’t see as many Commodore 16s as we should. A recent feature showed a 64k C16, but didn’t make it into a C64.

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