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ble characteristic out

Sets a Bluetooth LE characteristic to each message's payload, for a connected device to read, and notifies the devices that subscribed.

Properties

  • service UUID / characteristic UUID — as for ble characteristic in.
  • encoding — how payload becomes bytes: the same choices. Default bytes. A number must fit: 70000 doesn't fit an int16.
  • notify — also push each new value to the devices subscribed to it. Default on.
  • BLE — the flow's BLE config.

Wiring

Input — payload is the new value. Unwired, the characteristic exists but stays empty.

This node has no output.

Behavior

Each message replaces the value. A device that reads gets the whole value; a notification carries up to 20 bytes unless the device has agreed a larger MTU (most do, up to 244). Only devices connected at the time are notified.

One characteristic out node per characteristic: two would fight over its value. A ble characteristic in on the same UUIDs makes it writable too.

Errors

A missing or malformed UUID, two out nodes on one characteristic, or a board without the ble nodes stops the deploy. A payload that doesn't fit the encoding is reported on the console and dropped, and the last value stays.

Anyone in range can connect and read: don't put anything private in a characteristic.