CPU-less Unhealthy Apple Animation on a 20×4 Character LCD From a 32K EEPROM

Animations on a dot-matrix show are simple, even with the bottom energy microcontrollers. However, what occurs should you take the microcontroller out of the circuit? Can you continue to get an affordable animation? An aspiring electronics geek, Ian Ward, proves you possibly can! This mission performs the “Unhealthy Apple” animation on a 20×4 character LCD from a 32K EEPROM. In different phrases, no CPU is required!

The unique “Unhealthy Apple” video is a stop-motion monochrome animation with 6,569 frames. The title comes from the Japanese dance-pop tune, “Unhealthy Apple!!” which can be sometimes the video’s soundtrack. Through the years, many renditions have appeared on numerous platforms. Unhealthy Apple is a well-liked demo on retro-computers. There may be even a port out there for the TI-84 graphing calculator.

In contrast to these ports, this mission has no CPU. Ward confronted the principle problem of becoming the Unhealthy Apple animation’s frames into 32,768 bytes. Then had to determine methods to switch these bytes to a 20×4 character LCD utilizing solely a 555-based clock working at 150 Hertz.

The fast math of the AT28C256 EEPROM’s bytes divided by the variety of video frames comes out to about 5 bytes per body. Fortuitously, a lot of every body is strong white (empty) or strong black (crammed). Ward cleverly used a mix of ASCII, empty, and strong characters within the controller’s ROM and eight characters in RAM to successfully reproduce visually recognizable frames.

Once more, there is no such thing as a CPU concerned within the playback. If we even have to name it this, the one caveat is the 256-byte lookup desk to map instructions and knowledge to the HD44780. With this association, there are successfully eight operations out there to the programmer.

Because the video above reveals, the result’s impressively placing.

On the surplus.org weblog, yow will discover particulars on how Ward mapped the characters. Future posts will cowl the video encoding. However for many who need to dive in immediately, take a look at the code in this GitHub repo.