Refresh Rate

Tri-color e-ink cannot redraw more than once every three minutes. The display driver enforces this, and refreshing sooner would damage the panel.

This makes the board a bulletin board rather than a chat window. A message that arrives right after a refresh waits for the next one. The board queues it and redraws as soon as the panel allows.

The NeoPixel is how you know a press or a message registered before the screen catches up.

The board also redraws every thirty minutes on its own, so the battery level, air readings, and forecast stay current even when no messages arrive.

Header

The top of every view shows the same three things.

• The name of the current view on the left
• CO2 in parts per million, temperature, and humidity in the middle
• Battery percentage and estimated runtime on the right

Runtime reads as 72% 14h on battery, or 72% +3h while charging, where the second number is time to full. A reading with no second number means the battery is holding steady and an estimate would be noise.

Status Bar

The bottom of every view shows how many messages are held and the signal strength of the last packet heard, in dBm. A number closer to zero is a stronger signal. Around -90 is a normal indoor reading.

Button

Press the button to move to the next view. The order is weather, then messages, then nodes, then back to weather.

Switching views does not reboot the board, so messages received earlier are still there when you come back.

Weather View

The current conditions row shows an icon, the temperature, and a description, all in red. Sunrise, sunset, and the moon phase sit on the right.

Below that is a three day forecast with a high, a low, and a description for each day.

The bottom half of the screen shows the two newest messages.

The forecast updates every thirty minutes. WiFi is only used for this, and the rest of the board works without it.

Messages View

Messages are listed newest first. The newest one is drawn in bold red so it reads from across a room. Older messages are black.

A long message drops to a smaller size so it does not crowd the others off the screen. It stays red.

The board shows as many complete messages as fit. It never cuts one off partway. When messages do not fit, the status bar reads something like 3 shown, 5 older.

Nodes View

Every radio the board has heard is listed, strongest signal first. Each row shows the node name, its ID, the signal strength, and how many packets have come from it.

A node shows its short name once it has sent a NodeInfo broadcast. Until then only the ID appears, which looks like !09d43fc8.

Node names are saved to the Feather's non-volatile memory, so they survive a reboot. Without this, the board would show raw IDs until every node happened to announce itself again, which can take up to three hours.

Sending a Message

Any node on the same channel can send to the board. Pair a Meshtastic node to your phone over Bluetooth, set the region to match your board, and send a message on the default channel.

The board is receive only. It listens to the mesh but never transmits, so it will not appear in anyone's node list.

Battery Life

The board runs for over a day on a 2000mAh battery.

E-ink draws power only while redrawing. Most of the remaining draw is the radio listening and the processor waking to check for packets. The board light sleeps between checks and wakes on the radio's interrupt pin, so nothing is missed while it naps.