mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
65 lines
1.0 KiB
C++
65 lines
1.0 KiB
C++
//
|
|
// FILE: MHZCO2_PWM.ino
|
|
// AUTHOR: Rob Tillaart
|
|
// PURPOSE: demo MHZ library / sensor
|
|
// DATE: 2020-09-01
|
|
|
|
|
|
/*
|
|
DATASHEET P.?
|
|
Conversion between PWM output and concentration,
|
|
use interrupt pin 3 of Arduino UNO.
|
|
*/
|
|
|
|
|
|
#include "Arduino.h"
|
|
#include "MHZCO2.h"
|
|
|
|
|
|
// adjust to calibrate.
|
|
const float MAX_CONCENTRATION = 2000.0;
|
|
|
|
volatile uint16_t width;
|
|
|
|
|
|
void IRQ()
|
|
{
|
|
static uint32_t start = 0;
|
|
int v = digitalRead(3);
|
|
if (v == HIGH) start = millis();
|
|
else width = millis() - start;
|
|
}
|
|
|
|
|
|
uint16_t PWM_concentration()
|
|
{
|
|
noInterrupts();
|
|
uint16_t TimeHigh = width; // milliseconds
|
|
interrupts();
|
|
|
|
uint16_t concentration = round(((TimeHigh - 2) * MAX_CONCENTRATION) * 0.001);
|
|
return concentration;
|
|
}
|
|
|
|
|
|
void setup()
|
|
{
|
|
Serial.begin(115200);
|
|
Serial.println(__FILE__);
|
|
Serial.print("MHZCO2_LIB_VERSION: ");
|
|
Serial.println(MHZCO2_LIB_VERSION);
|
|
|
|
attachInterrupt(digitalPinToInterrupt(3), IRQ, CHANGE);
|
|
}
|
|
|
|
|
|
void loop()
|
|
{
|
|
Serial.println(PWM_concentration());
|
|
delay(1000);
|
|
}
|
|
|
|
|
|
// -- END OF FILE --
|
|
|