Fuji Electric NRF51 User Manual page 27

4.4.1.3 Icon display
Wi-Fi icon
(1) Wi-Fi icon flashes: Connection processing in progress or searching for radio waves
(2) Wi-Fi icon turns on: Active (connection established)
(3) Communication prohibition icon turns on: Low battery voltage
(4) No icon: OFF
Attention
Communication prohibition icon
Please make sure that there is no obstacle such as a metal object between
NRF51 and Wi-Fi access point in Wi-Fi communication. If there is the obstacle,
communication may be unstable and sending data may be lost.
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