1.2 LED Indicators
The development board features four LEDs that can be used to provide diagnostic information for the demo code that comes with the board. At power-up, the LED array should flash twice in the following order: Blue, Green, Yellow, and Red. This will indicate that the board is pre-programmed. Each LED is assigned to indicate the status of a certain aspect of the IoT system, which can be found in the table below.
| LED Color | Type | Indication | Details | |
|---|---|---|---|---|
| Label | Pattern | |||
 Blue | WIFI | Solid Blue | Wi-Fi Network Connection | Indicates a successful connection to the local Wi-Fi network. |
| Blinking Blue (slow blink) | Soft AP Mode | Indicates that the board can be detected and used as a Wi-Fi access point. For details, refer to Section Via Soft AP. | ||
| Blinking Blue (fast blink) | Wi-Fi Network Connection | Indicates that the board is trying to establish a successful connection to a Wi-Fi network. In combination with a blinking green LED, it means that the board is trying to connect to the network using default Wi-Fi credentials. | ||
 Green | CONN | Solid Green | Google Cloud Connection | Indicates a successful MQTT connection to Google Cloud. |
| Blinking Green | Google Cloud Connection | Indicates that the board is trying to establish a MQTT connection to Google Cloud | ||
 Yellow | DATA | Blinking Yellow | Data Publication to the Cloud | Indicates that sensor data in the form of MQTT packet has been successfully published to Google Cloud. |
| Solid Yellow for ON state, LED Off for OFF state for extended time | State of Toggle sent within MQTT publish packet | Indicates the state of the Toggle switch (ON = 1 / OFF = 0), received as part of the packet published by Google Cloud on the subscribed topic. | ||
 Red | ERROR | Solid Red | Error Status | Indicates an error in the application. |