2.4 - Comm and Control LEDs [UE9 Datasheet]

There is a yellow LED associated with the Comm (communication) processor, and a green LED associated with the Control processor.

The Comm LED flashes on reset and USB enumeration, and then only turns on when there is communication (USB/Ethernet) traffic. This LED then turns off if there is no communication for about 200 ms.

The Control LED normally blinks continuously at about 2.5 Hz. In flash programming mode it blinks at about 8 Hz. If the LED is blinking at about 0.5 Hz, that signifies the deprecated (no longer supported) low power mode. Those blink rates apply when the UE9 is idle, as this LED also flashes on Control processor activity.

Normal Power-Up LED Behavior: When the USB cable is connected to the UE9 (no other connections at all and no software running), both LEDs will start blinking. The Comm LED will blink a few times and then turn off. The Control LED will continue to blink continuously.