Hands-On Embedded Programming with C++17

Motion

The motion module is intended to work with passive infrared (PIR) sensors. These have onboard logic that determine when a trigger point has been reached, at which point they change an interrupt pin into a high signal. We can use this to determine whether a person is in a room, or is walking through a hallway.

Its code looks as follows:

#include "base_module.h" #define GPIO_PIN 0 class MotionModule {    static int pin;    static Timer timer;    static Timer warmup;    static bool motion;    static bool firstLow; public:    static bool initialize();    static bool start();    static bool shutdown();    static void config(String cmd);    static void warmupSensor();    static void readSensor();    static void IRAM_ATTR interruptHandler(); };

Of note here is that we explicitly ...