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ble notify

Subscribes to a characteristic of another Bluetooth LE device and sends a message each time it sends a new value.

Properties

  • BLE peer — the device to listen to. Required.
  • service UUID / characteristic UUID — the characteristic: 16-bit or 128-bit. Required. It must support notify or indicate; nRF Connect shows which.
  • encoding — how each value becomes payload, as for ble read. Default bytes. It also sets the output's type.

Wiring

Input — none. ble notify is a source.

Output — payload is the value. The message also carries peer, the device's address or name, and uuid, the characteristic.

Behavior

The board turns notifications on when it connects, and again after each reconnect. It uses indications when the characteristic offers no notifications. Up to 20 values wait if they come faster than the flow handles them; then the oldest are dropped.

Errors

A characteristic that can't notify or indicate is reported when the board connects. A value that doesn't decode is reported and dropped.