Why do the gadgets only support 2.4 GHz WiFi?

Because that’s the radio in the silicon: the ESP32’s WiFi hardware speaks 802.11 b/g/n on 2.4 GHz, period. It’s a genuine limitation worth knowing before you buy, but it comes with a consolation prize: 2.4 GHz travels farther and through walls better than 5 GHz, which suits a gadget that lives wherever it looks best rather than next to the router.

Why a resistive touchscreen instead of capacitive like a phone?

Resistive touch registers pressure, not skin, so it works with a fingernail, a stylus, or winter gloves, and it never misreads a stray splash. For an interface that’s essentially ‘tap to change screens,’ it’s reliable, repairable, and honest. These are instruments, not phones.

Is there a Raspberry Pi inside?

No, and that’s a feature. A Pi is a full computer with an operating system, a boot sequence, and an SD card that can corrupt when power drops. The ESP32 is a microcontroller: it runs one purpose-built program, boots in seconds, shrugs off power cuts, and draws a couple of watts doing it. For a single-purpose device that runs 24/7, less computer is more.

The board supports a battery. Can the gadgets run cordless?

The board has a lithium battery charging circuit built in, but PlankLabs gadgets are designed as always-on, plugged-in desk instruments. A WiFi radio plus an always-lit backlight makes battery life short enough that I’d rather not pretend otherwise. The circuit is headroom for future ideas, not a hidden feature.

The Board Inside Every PlankLabs Gadget

Seven different gadgets, seven obsessions, one heart. Every product in the PlankLabs lineup is built on the same board: an integrated module that fuses an ESP32 microcontroller to a 3.5″ color touchscreen on a single PCB, with USB-C power, a microSD slot, and every peripheral a desk instrument needs, documented publicly on LCD Wiki if you want the full datasheet experience.

Here’s the tour, and the reasoning.

The brain: ESP32

The compute side is an ESP32-32E module — a dual-core processor running at up to 240 MHz with 520 KB of RAM, 4 MB of flash storage, and the important part: WiFi and Bluetooth in the same chip. This one component is why a PlankLabs gadget needs no hub, no app, and no companion hardware. The chip that draws the radar screen is the same chip talking to the network.

Those numbers sound quaint next to a phone, and that’s the point. A phone runs a thousand things adequately; this runs one thing — fetch live data, draw it beautifully, respond to taps — with full attention. Two cores means the firmware can keep the display silky on one core while the other negotiates with a weather server. There’s no operating system in the desktop sense and no updates that rearrange your furniture: power on, and a few seconds later the gadget is doing its job.

It’s also why the setup experience works the way it does. The ESP32 can be a WiFi access point, which is the entire captive-portal trick: the gadget broadcasts its own network, your phone joins it, a settings page appears, and thirty seconds later the gadget hops onto your home WiFi. And when improvements ship, the same radio pulls down over-the-air firmware updates on its own.

The face: 3.5 inches of honest pixels

The display is a 3.5″ TFT panel at 480 × 320 driven by an ST7796 controller — six white LEDs of backlight pushing 300 nits, which is comfortably readable across a room. On top sits a resistive touch layer (an XPT2046, for those keeping score) that registers deliberate pressure rather than capacitive skin contact.

The panel speaks to the ESP32 over SPI — a modest data pipe by modern standards, and honestly one of the more interesting engineering constraints in the whole product. Pushing lively, animated screens through that pipe without stutter is a discipline: you redraw what changed, not the whole screen, and you earn every frame. When people say the displays feel smoother than they expected, that’s not the hardware being generous — that’s the firmware being careful. (More on that in the Arduino post.)

The rest of the board

The module carries more capability than most of the gadgets use: a microSD slot, a battery-charging circuit, an audio DAC with speaker support, an RGB indicator LED, and spare I/O pins brought out to connectors. None of it is wasted; it’s headroom. Seismic Sentinel, for one, puts the RGB LED to work as a status light that breathes cyan while it runs and changes color when an alert takes over the screen for a quake the USGS has already posted. When a future gadget wants to chime on an ISS pass or log data to a card, the hardware is already sitting there waiting for firmware to give it a job.

Why one board for everything

A one-person lab could chase the perfect bespoke board for each product. Instead, every PlankLabs gadget shares this one platform — and that choice does a lot of quiet work:

Fewer failure points. An integrated module means no ribbon cables between separate screen and brain boards — the connector that isn’t there can’t work loose in shipping.
One platform, deeply known. Every quirk learned building the weather station makes the tide clock better. Validation, testing, and the OTA update system are built once and trusted seven times.
Assembly that scales to one person. Same board, same mounting, same USB-C placement — the 3D-printed shells differ, the heart never does.

It’s the small-shop version of a platform strategy: pick one honest, well-documented piece of hardware, learn it to the bones, and spend the saved energy where buyers actually feel it — the screens, the data, and the reliability.