Connecting an ultrasonic sensor to the microcontroller board

Before moving ahead, we need to learn about the functionality of the HC-SR04 ultrasonic sensor, how to interface it with the STM32 Blue Pill, and how to write a program to measure the distance between the sensor and another object.

This sensor emits an ultrasonic wave. When this wave collides with an object, the wave is reflected and received by the sensor. When the reflected signal is received, the sensor can calculate the time it took to be reflected, and thus the distance of the collision object can be measured.

The sensor can be seen in the following screenshot:

Figure 13.5 – Ultrasonic sensor

This sensor board connects to the STM32 Blue Pill microcontroller board with four pins, outlined as follows:

• Trigger: This pin enables the ultrasonic wave.
• Echo: This pin receives the reflected wave.
• VCC: The pin to supply power to the sensor (5V).
• GND: Ground connection...