We want to generate some random numbers. For simplicity, we'll assume we want a random number between 1 and 100. We want our random-number generator to be:
Public (everyone knows the same random numbers, at roughly the same time)
Fair (every number has the same odds of coming up)
Trustable (everyone knows it's fair--it should be above doubt)
Fast (we want to generate as many numbers as possible, as often as possible)
Unpredictable (you shouldn't be able to guess the result before it's revealed)
Some security experts suggest that a trustable system should also be:
Decentralized (no single person, organization, or computer picking the numbers). This is because a central trusted group requires faith in that group and its security.
One for this in the real world was the "Numbers Game", a popular illegal lottery in the 1800s, in the USA. The winning numbers were selected at random each day, like most lotteries--by the mob. After complaints about rigged lotteries, the winning numbers started to be picked more transparently. For example, it might be the closing price of the New York Stock Exchange--just the cents value. For a hundred dollar lottery, you would be crazy to worry about someone messing with the New York Stock Exchange. (But if it became a billion- or trillion-dollar lottery, you should worry again.)
The biggest problem with using a stock exchange that it's slow. You only get one set of numbers a day.
Can you come up with a better random-number generator?
Using electrical tape, I split a whiteboard into sections. Voila, whiteboard calendar.
A teacher friend of mine already knew exactly how to do this--apparently it's common knowledge among teachers.
I did look if there were either large, disposable calendars (no) or existing whiteboard calendars (they're laminated posters that don't actually erase). A 3ft x 2ft (1m x 0.6m) whiteboard costs $30, and you can get electrical tape for $1.
The stickers look bad--I half-assed them. I need tons of big stickers or none at all. This was way too tentative. I do want some kind of decoration, though.
In 2022, 2023, and 2024, I did "Hack-a-Day", a challenge to myself to do one project a day for all of November. It's vaguely modelled off NaNoWriMo, a challenge to write a book in November.
This year, I completed 21 projects in 30 days. On average, I worked 7.5 hours per project. My expenses for the month were $130, divided over only three projects--ingredients for Project L.E.M.B.A.S. ($85), aluminium to mill for soma cubes ($28), and missing parts for my TODO whiteboard ($19).
To see a list of all projects from this year and previous ones, check out my hack-a-day website.
Having prepped my ESP-32, I decided to make an LED fireplace today.
The plan was to put an LED strip on a piece of cardboard, and have slowly shifting red, orange, and yellow lights going up and down, somewhat like a music visualizer. I knew the bare LEDs wouldn't look good, so the plan was to put the cardboard somewhat deep into the fireplace, and add some translucent tissue paper layers in front to diffuse the lights.
vertical 'strips' of lights
Sadly, of my three ESP-32s, two were broken. I ended up instead using an ESP-8266, since I had several laying around. Annoyingly, the boards I have are so wide it's impossible to breadboard the, so I used perfboard instead.
Having carefully set up the circuit, I flipped the on switch and... nothing happened. It was about 10pm at this point, and I was starting to run out of energy, so I gave up.
Very late that night, I found the problem was the resistor I added--the LED strip has a built-in resistor as well, and apparently the two together were too much. I eventually got the lights to turn on, but too late to finish the project for the day.
my test pattern looks a little christmas-y
A while back, I was trying to set up a power monitoring system, and I mistakenly bought the wrong ESP dev board. The ones I ended up are sold by some fake-named Chinese manufacturer. They seem pretty fine, much like any other ESP32 dev board, but they have an unusual 30-pin layout.
I tried to add some electronics to my whiteboard hack earlier this month, but got frustrated pretty quickly, failing to program the microcontroller, and with no idea what the pinout was.
Today I decided to take it slower. I'd figure out how to program it, and understand the pins. If I had any time left over, I'd do a project.
First, I got flashing the chip to work. It turns out my main problem from the first time was a bad upload serial rate. I debugged the problem with the help of friendly folks on IRC. Espressif (the ESP32 manufacturer) has helpful troubleshooting instructions, which suggest using the python serial terminal, miniterm. By taking a step at a time, I got the microcontroller working.
Next, I installed and set up platformio, which I had never used before. My experience was that it was pretty good once set up, but a little hard to get started on the command line. Still, I'm happy, and will probably use it again. Platformio has two options--the popular Arduino framework libraries, or the Espressif-provided esp-idf libraries. Based on the small code samples I found, I'll most likely use the Arduino libraries, but some specialty features are just not available on Arduino.
Finally, I set up platformio one last time, with the VS-Code based PlatformIO IDE. Again my experience was pretty good. Sadly, the open-source VS-Code does not show the same set of extensions, and I had to use the binary version. (Aside: Come on, vs-code. Don't call your package and program code. That's a dick move.)
The writeup of how to get your dev environment set up is on github.
Finally, I made the below pinout diagram with the rest of my night.
the colors looked better when it was bigger, I swear
