Overview of Firmware and IoT Networking

• Board running firmware
• Server on the network

What you will learn

• Say how firmware is built and flashed.
• Understand the setup() and loop() cycle.
• Explain why MQTT suits IoT devices.

Before you start

It helps to know what an ESP32 or Arduino board is.

How is firmware built and flashed?

ESP-IDF is the official development framework for the ESP32 series of chips. A simple example shows how to build and flash firmware onto an ESP32 board.

• Computer with ESP-IDF
• Built firmware
• ESP32 board

How do setup() and loop() run?

The setup() function runs once when the sketch runs. The loop() function repeats continuously.

• setup() runs once
• loop() runs
• Back to loop()

How does MQTT put data on the network?

MQTT is a Client Server publish/subscribe messaging transport protocol. MQTT is light weight, open, simple and designed to be easy to implement. At QoS 2, message delivery is exactly once in the protocol exchange; this alone does not guarantee exactly-once application processing end to end.

On security, NIST publishes guidance for manufacturers and supporting parties creating IoT devices and products.

• Publishing device
• MQTT server
• Subscriber
• Security guidance

Real-world example

With an adult, think of a soil moisture sensor. In this hypothetical example, an Arduino sketch reads the sensor in loop(), then sends the reading over MQTT for an app to show.

Common misunderstandings

Every firmware uses setup() and loop(). Those functions describe the Arduino sketch structure; other frameworks, such as ESP-IDF, use different program structures.

MQTT is a heavy protocol, hard to use on small devices. MQTT is light weight, open, simple and designed to be easy to implement.

Frequently asked questions

What is ESP-IDF?

The official development framework for the ESP32 series of chips.

How do setup() and loop() differ?

setup() runs once, while loop() repeats continuously.

What is MQTT?

A publish/subscribe messaging transport protocol.

Who publishes security guidance for IoT devices?

NIST publishes guidance for manufacturers and supporting parties.

Summary

• Firmware is built with a framework such as ESP-IDF and flashed onto the board.
• In Arduino sketches, setup() runs once and loop() repeats continuously.
• MQTT is light and simple, and NIST has guidance for manufacturers.