2.4.3 Sending the Messages

The AVR-IoT webpage displays a section called What's Next, two sections below the Light and Temperature graphs. In this section, users can go through the steps of building their own custom application. To quickly preview the capability to send messages from the Cloud to the board, click the Implement a Cloud-Controlled Actuator () icon, and then click the Learn More button to expand the section.

Figure 2-8. What's Next
Scroll down to the Control Your Device section. Here, control mechanisms can be seen:
  • The Toggle button is used to send the switch value to the AVR-IoT WG board.
  • The Slider is used to send a numerical value on the slider scale to the AVR-IoT WG board.
  • The Text field is used to send text to the AVR-IoT WG board.
Users can add multiple instances of these controls by clicking the Add button at the right-hand side of the page.

The values are only published over the ‘/devices/{deviceID}/config’ topic upon pressing the Send to device button. Since the board subscribes to this topic by default, all the published messages are received by the board. The payload received here is limited by the MQTT Receive Buffer (bytes) configurable in MQTT library MCC window (see Figure 3-12 for more details).

Figure 2-9. Sending Messages on the Subscribed Topic