//This code based off the one from Waveshare. Some small edits were made #define COV_RATIO 0.2 #define NO_DUST_VOLTAGE 400 #define SYS_VOLTAGE 500 /* I/O define */ const int iled = 7; const int vout = 0; /* variable */ float density, voltage; int adcvalue; /* private function */ int Filter(int m) { static int flag_first = 0, _buff[10], sum; const int _buff_max = 10; int i; if(flag_first == 0) { flag_first = 1; for(i = 0, sum = 0; i < _buff_max; i++) { _buff[i] = m; sum += _buff[i]; } return m; } else { sum -= _buff[0]; for(i = 0; i < (_buff_max - 1); i++) { _buff[i] = _buff[i + 1]; } _buff[9] = m; sum += _buff[9]; i = sum / 10.0; return i; } } void setup(void) { pinMode(iled, OUTPUT); digitalWrite(iled, LOW); Serial.begin(9600); } void loop(void) { /* get adcvalue */ digitalWrite(iled, HIGH); delayMicroseconds(280); adcvalue = analogRead(vout); digitalWrite(iled, LOW); adcvalue = Filter(adcvalue); /* covert voltage (mv) */ voltage = (SYS_VOLTAGE / 1024.0) * adcvalue * 11; /* voltage to density */ if(voltage >= NO_DUST_VOLTAGE) { voltage -= NO_DUST_VOLTAGE; density = voltage * COV_RATIO; } else density = 0; /* display the result */ Serial.print(density); Serial.print(" ug/m3\n"); delay(1000); }