Connecting Sensors and Actuators with ESP32

In this chapter, we will dive into the world of sensors and actuators with the ESP32, a highly versatile and powerful microcontroller. By exploring its built-in features and connectivity options, you will develop a fundamental understanding of how to interact with the physical world using advanced pieces of hardware.

We will start with the introduction to the ESP32’s general purpose input/output (GPIO) pins and their functionality. Next, we will learn about universal asynchronous receiver-transmitters (UART) and serial communication, which will enable us to exchange data between devices. After mastering UART, we will turn our attention to the serial peripheral interface (SPI) communication protocol, a method commonly used to send data between microcontrollers and small peripherals. Finally, we will delve into I2C communication, a highly efficient two-wire protocol used for short-distance data transmission.

To truly understand...

Technical requirements

For this chapter, we will need the following components:

• ESP32 dev kit
• Push button
• LED
• DS1307 RTC module
• PN532 RFID module

Getting hands-on with ESP32 GPIO pins and an overview of them

GPIO is a fundamental feature found in microcontrollers and other embedded systems. It refers to the ability of the microcontroller to interact with the external world by providing a flexible set of input and output pins. GPIO pins can be configured to either read or write digital signals, allowing the microcontroller to communicate with various devices and peripherals. As input, GPIO pins can detect the state of external sensors, switches, or digital signals. For example, we can read the temperature from temperature sensors. As outputs, they can drive LEDs, control motors, or interface with other electronic components. The versatility of GPIO pins makes them essential for a wide range of applications, enabling the microcontrollers to interact with and control the physical environment.

In this section, we will dive into ESP32 GPIO pins and explore their potential. By understanding this topic, you will be able to control...

Mastering UART communication

A UART is a hardware device or a protocol that manages asynchronous serial communication between devices. It facilitates data transmission by converting bytes of data from the CPU into a continuous stream of bits suitable for transfer via communication links. One of the key features of UART is that it does not require a clock signal. This simplifies hardware, reduces power consumption, and allows flexible data rates but may also lead to potential timing and synchronization issues between the sender and receiver, requiring additional overhead for start and stop bits and making it less suitable for high-speed or long-distance communication. The absence of a clock signal makes this protocol asynchronous. This simple yet powerful communication protocol is commonly used in microcontroller-based projects for inter-device communication, making it an essential part of our ESP32 study.

In this section, we will cover the following topics related to UART in the...

I2C communication with ESP32

I2C is another serial communication protocol, but unlike the UART protocol, it is a synchronous communication protocol that is used for communications between integrated circuits or devices on a shared bus. Since it is a synchronous communication protocol, it requires a clock signal and works in the master-slave architecture. Therefore, it is commonly used in scenarios where multiple devices need to communicate with the master/central device.

In this section, we will explore the following topics related to I2C communication in the context of ESP32 and Arduino IDE:

• How I2C communication works
• I2C communication example using ESP32
• Sensors that use I2C communication

By the end of this section, you will be able to explain the I2C protocol, differentiate it from UART, use it with ESP32 using Arduino IDE, and understand some of the common sensors available on the market that can be interfaced using I2C.

How I2C communication works...

Understanding SPI communication

SPI is a synchronous serial communication protocol widely used for connecting microcontrollers or other digital devices with peripheral devices. It provides a straightforward and efficient means of data transfer, making it suitable for applications that require high-speed and full- duplex communication.

Like the I2C communication protocol, the SPI protocol uses a master-slave architecture, where one device acts as a master, controlling the communication, and one or more devices act as slaves, responding to commands from the master.

In this section, we will explore the following topics related to the SPI communication and ESP32:

• How SPI communication works
• SPI communication example using ESP32
• Sensors or devices that use SPI communication

By the end of this section, you will be able to understand what the SPI communication protocol is, how it works, how we can use it in ESP32-based projects, and some common peripherals in...

Summary

In this chapter, we learned about ESP32 peripherals and the functions of those peripherals. We learned how to use the IOs of ESP32 and how to use PWM. Furthermore, we discussed the most common serial communication protocols, such as UART, I2C, and SPI, in detail to help you connect many peripherals not only with ESP32 but also with other microcontrollers. We also learned how we can make two ESP32s communicate and how to interface RTC modules and RFID/NFC modules. The learnings of this chapter will make a strong foundation for developing IoT.

In the next chapter, we will discuss how to interface displays and cameras with ESP32.