Microchip Technology AVR-IoT WG User Manual page 23

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Operation Mode
Programming
Fault
Sleep/Off
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2018 Microchip Technology Inc.
AVR-IoT WG User Guide
Appendix A: Hardware Components
Status LED
Activity indicator; the LED flashes slowly during
programming/debugging with the nEDBG
The LED flashes fast if a power fault is detected.
LED is off. The nEDBG is either in Sleep mode or
powered down. This can occur if the kit is
externally powered.
User Guide
DS50002809A-page 23