I’ve been wanting to make a 1:220 scale megacity diorama and don’t know what options I have. I’m projecting I’ll need to control the speed of two motors, some LEDs, and maybe a dozen or so tiny screens as digital billboards. It’s the screens I’m worried most about.
I’d like to scavenge digital displays from e-waste, group them by type/resolution, and have a slideshow for each group that rotates throughout the city.
My initial idea was to use digital photo frames, but they’re too big, and used ones are still too expensive for the quantity I need.
I’m assuming I will need multiple controllers(/processors?), but I don’t know enough terminology to find what I need. I’m still thinking out the diorama, so if it’s too hard/expensive I can just do backlit decals, but that’s boring.
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I do model building with LEGO, and I use the Raspberry Pi Pico (which is different from a Raspberry Pi). For programming, I use the Arduino environment.
The controller has two cores, and, in the version I use it, has a wifi interface.
My models are modular and have a 12V power bus, and I use DC/DC adapters to generate the 5V or 3.3V needed for some applications. I use 12V because some lights and many motors needs them.
The controller has over 20 IO pins, lots of options for i2c and SPI busses, and the PIO system allows for easily driving NeoPixel displays.
The wifi is used to connect the processors to a central Mosquitto broker, so they can communicate, e.g. coordinating light effects or reacting to a button press somewhere.
The atmega328 and stm32f411 are good. Both are well documented, have boards available with good peripherals, and plenty of other hobbyist projects on them.
The atmega328 is 8-bit. It was made by Atmel, which was a great company until they got bought by Microchip a decade ago. Their IDE sucks now, but you can still program them with other tools and IDEs.
The stm32f411 is 32-bit, a bit more recent, and a bit more expensive. ST microelectronics has great documentation and hobbyist support.
These are microcontrollers, so you’ll be running without an operating system. If you want embedded Linux, you’ll need something with an MMU and more power than a microcontroller.
The atmega328 was a fine option a decade ago, and I still love them, but they aren’t what I’d recommend to someone new. The Pi Pico or an ESP32 make more sense in the current day.
This seems like a project that doesn’t need super high performance nor tight timing requirements (for anything other than driving displays), so I’d recommend considering Circuitpython or Micropython instead of C++.
I don’t know shit about shit, but I really want to see your WIP and finished pics! This sounds like an awesome project.
ESP32-S3 will do everything you want and then some. And you can do it all without any programming by using ESPHome. And they are incredibly cheap (starting around $3 a board and up depending on options).
There are more suited, fancier, better options, like using STM32FX microcontrollers, but that will require more knowledge, programming skills, and you’ll find it harder to get help.
Esphome is not going to run random displays
Wonder what’s running this display then
Considering there’s not much else on this board
TBF, nothing was running the display when you took the pictures!
That’s fair. It was a $10 Bitcoin lottery miner and it auto boots to the mining software and I didn’t want to give them free advertisement.
But trust the display works.
I’ve no doubt; I’m just teasing!
I cant see the code in this picture…
? That’s like the one thing that’s super visible. It starts with “ESP32”.
ESPhome is software that generates code, ESP32 is hardware.
I know the hardware is capable.
Oh, my bad. I thought you were talking about the silicone. I don’t really consider myself a bright person. Again super sorry if I sounded rude.
It sure does, with its in-house display library, nexion displays, or LVGL.
Thanks, I’ll look into that!
I don’t have the answer to your question but I applaud your ambition and willingness to reach out to the community before hand for help.
The main thing is that (as a relative novice) you’re going to want something with a good community around it. Therefore, you want either Arduino, ESP32, or Raspberry Pi Pico.
There’s a bunch of different ones with different features that may have varying usefulness for your particular situation, so nobody can tell you exactly which ones to get down to the model number. You’re just going to have to read the data sheets to figure out which to buy.
Regardless, any reasonable choice ought to be obtainable as off-brand clones in a multi-pack from Aliexpress for single-digit dollars per unit.
Personally I’m a big fan of Adafruits ItsyBitsy 32u4. Loads of potential in a small and cheap backage. Enumerates as an arduino via the USB port, so no special hardware is requires to program it. I use one to read a PWM signal and measure the pulse width on a few channel, so I would think it’s capable of outputting similar signals, which comes in handy for contrilling LEDs and small steppers.
If you want to control something a bit more power hungry via PWM you might want to look into PCA9685 which works really well with, for example, a raspberry pi zero.
What kind of scavenged screen? Laptops? Because non-laptop small lcds are an undocumented mess. You’d do better to buy screens that work with esp32s.
Undocumented mess, here I come
Edit: Some of these are actually pretty affordable. Hmmm
I think if you don’t already have a more solid plan than that, then this project is probably too complicated for now, and you might start with a single display. If the origina megacity is 22 miles across (fairly small for a megacity) then 1/220th of that is 1/10th of a mile which is pretty huge. A standard 48 foot billboard would scale to 2.6 inches wide.
It’s a quasi-solid plan, lol. Most of the planning I’ve done has nothing to do with the question, so I left it out.
The diorama is only depicting a section of a larger, cyberpunk flavor city, and it’s going to sit on a 3ft2 card table. One of the motors is gonna drive an elevated rail with reed switches so it pauses at the stops, and the other motor is gonna drive continuous traffic from hell on the surface level. All that is already something I know how to do with older tech. It’s a homebrew variation on the Magnorail system, if you want to know more.
I’m aiming for the itty bitty displays, like you see in vapes and toys and shit. I might be able to fit a couple big ones on buildings like Times Square vibes, but generally not more than 3".
I might be insane, tbd.
Well, MCU programming and hardware is another thing to know about ahead of time, but ok. There are tons of displays of all sizes on waveshare.com if you want. Tons more on aliexpress. A standard large billboard is apparently 48 ft wide (per web search) so you’d want to scale accordingly. Maybe with e-ink to simulate a reflective billboard. OLED’s would be for neon signs and stuff.
I like the Raspberry Pi Pico because it’s very well documented, but yeah, ESP32 stuff might be cheaper.
Post some pics when it’s working!