I bought this tiny yellow cube off Aliexpress for about $18 (canadian monopoly dollars). There was no documentation, and no instructions on the listing. There was just a photo and a very short description containing "development board". Obviously, I had to figure out how to make it do something. That's the type of gambling I do.
I love to browse Aliexpress to find random shit. Sometimes, it's just to laugh at the ridiculous products or creative descriptions. Sometimes, I can't resist and buy some stuff to play around with.
I just received a cute display. I don't know yet what I'm going to do with it. The listing did not say much, and I did not research it a lot. I just impulsively pressed the "add to cart" button and let future (now present) Sophie the pleasure to discover what's inside.
So, today I'm opening it up to document what's inside. Maybe some ideas will come soon. So far, the best idea I have is to code a custom and cute desk pet/robot/companion that does nothing useful other than being a cute companion.
The display from the front, a cute yellow cube with a small dark screen recessed into the top face
The back of the device showing ventilation slits, a button, and a USB-C port for power
It slides open, and I immediately notice that there is plenty of room to cram some stuff in there if I want to. Maybe I'll add a battery?
The main PCB slid out of the case, revealing an ESP-12S WiFi module and the board labeled "ESP 1.54 LCD V1.0" by ZJYUNJIE
Close-up of the ESP-12S module with its FCC ID (2AHMRESP12S), CE marking, and the PCB antenna.
There's also a 4-pin JST-style connector labeled VG54 on the board. The traces appear to route toward the right side of the ESP-12S, possibly to GPIO14 (SCL) and GPIO12 (SDA) — which would make it an I2C expansion port. A continuity test with a multimeter would confirm it.
I noticed that some listings are mentioning a capacitive touch on the top of the device, but the one I bought does not have that. This is probably where it would be plugged in.
The other side of the PCB showing the display flex cable connector and several surface-mount ICs
The ribbon cable is marked "FP-154HSC04B" with "JY" underneath. No separate touch controller or extra FPC is present, so this is likely a display-only panel without touch input.
The U3 IC turns out to be a CH340K by WCH — a USB-to-serial converter. This means the USB-C port isn't just for power, it's for programming the ESP-12S directly over USB. That is going to make projects easy to flash! :D
I used the ESP8266 and ESP32 in many projects in the past, and attempted to do something useful with the tiny but very limited ESP-01. It's the first time I get to play with an ESP-12S, which is actually an ESP8266 in a specific module packaging with a built-in PCB antenna and 4MB flash.
As opposed to the good ol' ESP32 I know pretty well now, the ESP-12S has
So it makes a good low power and cheap alternative for simple projects.
Based on the board label "ESP 1.54 LCD" and the ribbon cable marked "FP-154HSC04B", this is a 1.54" IPS TFT LCD with a 240x240 resolution and 65K RGB colors. These panels are almost always driven by an ST7789 controller over SPI. No touch capability.
I just discovered the holy trinity of GitHub formatters and I'm having a moment. You know that annoying workflow where tests fail in CI and you have to click through Actions logs like you're on a treasure hunt? There are formatters that fix this for RSpec, RuboCop, AND Cucumber. All of them. Creating inline annotations right in your PR.
Today I learned Claude Code has hooks! These let you automatically run commands when certain events happen. I'm using this to auto-fix RuboCop violations every time Claude edits a Ruby file, and it's making my development flow so much smoother.
Today I discovered that Claude Code's slash commands can execute bash commands before running, capturing their output as context. This is making me so excited! When you have a bunch of commands to run, Claude is not always reliable for running the all, or running them in the right order.
I started working on the Octoprint gem back in March 2022. The goal was simple: create a Ruby wrapper around the Octoprint REST API so I could interact with multiple 3D printer servers for another project.
Simple, but incredibly boring.
The work was pure drudgery: read an API endpoint's documentation, create classes for models and errors, write tests, document everything, repeat. I implemented just what I needed and then... let it sit. For years. Untouched except for the occasional Dependabot update.
I was getting bored writing the CLAUDE.md file for my Ruby project. The usual drill: "Use RSpec for testing. Use Rubocop for linting." You know the type: bullet points that technically cover the basics but somehow miss the mark.
So I handed it off to Claude with a simple request: "Can you document conventions and commonly agreed-on best practices for this Rails project?"
What came back surprised me. Claude didn't just reformat my scattered notes; it completely restructured them. My lazy bullet points became a comprehensive guide with clear sections, context, and actionable details. The output felt more... intentional. Like it was designed to actually help someone succeed, not just check a documentation box.
But then, I realized Claude had essentially shown me how to write for its own "neurons."
That moment got me thinking. If Claude could improve my documentation, could it improve my prompts?