Hands-On Embedded Programming with C++17

PWM

The reason why the PWM module was developed was to have a way to generate an analog output voltage using an external RC filter circuit. This was in order to control the fan of the ceiling-mounted air-conditioning units, whose fan controller accepts a voltage of between 0 and 10 volts.

An interesting feature of this module is that it has its own binary protocol to allow for remote control, which is how the air-conditioning service can directly control the fan speeds via the ceiling-mounted nodes:

#include "base_module.h" #include <HardwarePWM.h> class PwmModule {    static HardwarePWM* hw_pwm;    static Vector<int> duty;    static uint8 pinNum;    static Timer timer;    static uint8* pins; public:    static bool initialize();    static bool start(); static ...