Getting started

The hardware, turning CAT on and off, the first-boot time zone prompt, the home screen, menus, and how saving works.

The hardware#

CAT has a 320×240 colour touch screen, eight buttons, a USB-C port, a microSD slot, a speaker, a set of air-quality sensors, a LoRa radio and Wi-Fi. A second, black-and-white e-paper screen shows the latest air readings even while the device is off.

Part	What it's for
D-pad `▲` `▼` `◀` `▶`	Move around menus, the home grid and the Explore world.
`A` and `B`	`A` accepts or opens; `B` goes back or cancels.
`START` and `SELECT`	Extra actions that depend on the screen (each page lists them).
Touch screen	Capacitive, one finger. Tap anything you could select with the buttons.
Power button	Wakes a CAT that is asleep or powered down. It does nothing while USB is plugged in.
USB-C port	Charging, connecting to a computer, and USB keyboards and mice.
microSD slot	Storage for GB Emulator games, their saves and Doom.
Speaker	Message chime, Party music, game sound.
Five RGB LEDs	Light shows from the Party menu.
E-paper screen	Always-visible air readings and the sleep screen (see e-paper badge).
Sensors	CO2, fine particles, VOC and NOx gases, plus temperature, humidity, pressure, light and motion sensors used internally.
LoRa radio	Long-range, low-power radio for the mesh messenger.
NFC tag	A phone tapped on the case reads a link to the project page and the device ID.

What's inside: four processors

Game processor (RP2350). Runs the screen, the apps, the Explore game and the mesh node that sends and stores messages.
Board controller (Nordic nRF5340 with nRF7002 Wi-Fi). Power, charging, battery gauge, Wi-Fi and saved networks, sensors, the e-paper screen, the clock and the NFC tag.
LoRa radio (RAK11300). Runs RNode radio firmware.
Crypto chip (Baochip). CAT's root of trust: it holds secrets and runs the cryptography behind the Crypto menu.

Power and charging#

Turning CAT on#

Plug in USB-C, or press the power button. A CAT that was put to sleep, powered down or ran flat wakes this way. The e-paper screen changes from ASLEEP to AWAKE Waiting for sensors..., and the first air readings appear about 30 seconds later.

Turning CAT off#

Open Settings → POWER and choose SLEEP, or POWER DOWN and then Yes. Either way, CAT shows Saving..., saves everything, shows GOODNIGHT and switches its battery off. The e-paper screen then shows a sleeping unicorn with Powered off. and Plug in USB-C to turn on.

When the screen goes darkThe screen dims and turns off after a while without input. CAT keeps running: it still receives messages, relays traffic for other CATs and reads the sensors. The first tap or button press on a dark screen only wakes it and does nothing else.

Battery and charging#

The battery icon is at the top right of the home screen and the Dashboard. It animates while charging.
Any USB-C charger works. A completely flat battery needs a proper charger (1.5 A or more) to start straight away; on a weak port CAT stays off until it has charged enough, which can take a while.
At 5% battery CAT saves everything automatically and briefly shows Critical battery Saving node.... If the cell gets too low, CAT saves and switches itself off, and the e-paper shows Battery empty.
The exact charge level, cell voltage and charger state are on Settings → DEVELOPER → INFO → POWER (see developer pages).

Charge at room temperatureCAT's charger doesn't monitor battery temperature, so it can't stop on its own if the battery gets too hot or cold. Charge CAT indoors and don't leave it charging in a hot car or in direct sun.

First boot: set your time zone#

The first time the home screen appears, CAT asks for your time zone. The clock and message times use it, and it is never sent over the network. The list works offline and knows daylight-saving rules up to the year 2100.

1. Pick a region with ▲ ▼ and A, or tap it. — 1. Pick a region with `▲` `▼` and `A`, or tap it.

2. Pick a country. The United States is first under Americas, the United Kingdom first under Europe. Seven per page; use NEXT PAGE.

4. Check the local time and choose SAVE TIMEZONE.

B goes back one step. Pressing B on the first page skips the prompt: the clock stays on UTC and CAT asks again at the next start. You can change the zone later in Settings → TIME & TIMEZONE.

The home screen#

Top bar: your device name, local time and date, battery. Bottom bar: the highlighted app and "Press A to open".

Five apps in a 3×2 grid: Dashboard, Garden, Explore, Chat and Settings.
Move with the D-pad. ◀ and ▶ step one tile (hold to repeat); ▲ and ▼ jump a row.
Open an app by releasing A, or tap its tile. If you move the highlight while holding A, releasing it does not open anything.
Unread messages show as a number on the Chat tile (99+ above 99).
The clock reads Syncing... for a moment after CAT starts.

Highlight on Chat, with 30 unread messages.

Using menus#

Settings and most sub-screens use the same list style.

Do this	With buttons	With touch
Move the highlight	`▲` `▼` (the list wraps around)	Touch a row
Open, run or tick a row	`A`	Tap the row
Change a <value> or a slider	`◀` `▶`	Tap the left or right half of the window
Go back one level	`B`	–

Rows with a small box are checkboxes: a filled box means on. Rows written as NAME <value> are steppers. Grey rows are unavailable.

A window with a status line, three steppers and an action.

How saving works#

CAT keeps your messages, contacts, settings and game progress in fast memory while it runs, and writes them to permanent storage at the moments listed below. If CAT loses power suddenly, or is reset, anything since the last save is lost.

CAT saves when you:

put it to sleep or power it down (Settings → POWER);
leave the Settings menu after changing something;
choose Settings → DEVELOPER → CONTROLS → FORCE SAVE;
start Doom, or enter the USB bootloader for a firmware update;
reach 5% battery (automatic).

While a save runs, a Saving... box covers the screen. An ordinary save takes about 4 seconds; a busy node can take 10 to 16 seconds. Don't unplug or reset during it.

TipUse POWER → SLEEP instead of letting the battery run out, and use FORCE SAVE before plugging CAT into a computer for an update.

Sounds and lights#

CAT plays the message chime (with NEW MESSAGE TONE on), an ambient loop in Explore, Party music, and game audio. The RGB LEDs light up from the Party menu.