Chapter 3: Expansion Modules
Last revision 2026/01/13
This article explores Arduino expansion modules with example codes for controlling LED and Buzzer modules as output indicators, and utilizing PIR sensors for enhanced robot interaction and feedback.
In chapter 2, we learned how to control the movement of the Devastator through programing. However, it’s still far from enough for the Devastator to be capable of interacting with people. In the following sessions, we will help you add even more functions to make our robot send feedback to the people nearby.
LED module and Buzzer module
LED module and Buzzer module are output modules controlled by digital signals. Due to simplicity, they are commonly used as light and sound indicators for robots.
In digital circuits, “LOW (0V)” represents for an “off” signal (0) and “HIGH (5V)” represents for an “on” signal (1). However, in practical, voltage of a signal may not be exact. Normally, the voltage of a LOW signal may range from 0V~0.25V and the voltage of HIGH a signal may range from 3.5V~5V. Take the LED module as an example, a LOW signal turns the light off while a HIGH signal turns the light on. The same rule also applies to the buzzer module. Check the circuit that
PIR sensor
The PIR sensor is an input module detects infrared radiations with wavelength around 10um exclusively radiated from human body. Its signaling mechanism can be described as following: when someone approaches the sensor, it sends out a HIGH signal as input, vice versa. Therefore, by adding this module, the robot will be able to take actions in reaction to someone passing by.
Was this article helpful?