Connecting an ultrasonic sensor to the microcontroller board
This section explains how an ultrasonic sensor works, and it describes how to connect the HC-SR04 sensor to the Blue Pill microcontroller board, describing how to use its four-pin functions. The ultrasonic sensor will be used to check whether the user waves at it to initiate the 20-second counting.
What is an ultrasonic sensor?
Ultrasonic waves are sound waves that have a frequency that is higher than the frequencies that most human beings can hear, which is above 20,000 Hz. Ultrasonic sounds, or ultrasound, can have different applications, including something called echolocation, used by animals such as bats for identifying how far their prey is using reflected sounds. The same principle is applied in ultrasonic sensors.
An ultrasonic sensor is a dedicated electronic component that generally contains a number of electronic parts such as resistors, transistors, diodes, a crystal clock, a special microphone, and a...