You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
140 lines
3.8 KiB
140 lines
3.8 KiB
// -----------------------------------------------------------------------------
|
|
// MICS-5525 (and MICS-4514) CO Analog Sensor
|
|
// Copyright (C) 2019 by Xose Pérez <xose dot perez at gmail dot com>
|
|
// -----------------------------------------------------------------------------
|
|
|
|
#if SENSOR_SUPPORT && MICS5525_SUPPORT
|
|
|
|
#pragma once
|
|
|
|
#include <Arduino.h>
|
|
|
|
#include "BaseSensor.h"
|
|
extern "C" {
|
|
#include "../libs/fs_math.h"
|
|
}
|
|
|
|
class MICS5525Sensor : public BaseSensor {
|
|
|
|
public:
|
|
|
|
// ---------------------------------------------------------------------
|
|
// Public
|
|
// ---------------------------------------------------------------------
|
|
|
|
MICS5525Sensor(): BaseSensor() {
|
|
_count = 2;
|
|
_sensor_id = SENSOR_MICS5525_ID;
|
|
}
|
|
|
|
void calibrate() {
|
|
setR0(_getResistance());
|
|
}
|
|
|
|
// ---------------------------------------------------------------------
|
|
|
|
void setAnalogGPIO(unsigned char gpio) {
|
|
_redGPIO = gpio;
|
|
}
|
|
|
|
unsigned char getAnalogGPIO() {
|
|
return _redGPIO;
|
|
}
|
|
|
|
void setRL(unsigned long Rl) {
|
|
if (Rl > 0) _Rl = Rl;
|
|
}
|
|
|
|
unsigned long getRL() {
|
|
return _Rl;
|
|
}
|
|
|
|
void setR0(unsigned long R0) {
|
|
if (R0 > 0) _R0 = R0;
|
|
}
|
|
|
|
unsigned long getR0() {
|
|
return _R0;
|
|
}
|
|
|
|
// ---------------------------------------------------------------------
|
|
// Sensor API
|
|
// ---------------------------------------------------------------------
|
|
|
|
// Initialization method, must be idempotent
|
|
void begin() {
|
|
pinMode(_redGPIO, INPUT);
|
|
_ready = true;
|
|
}
|
|
|
|
// Pre-read hook (usually to populate registers with up-to-date data)
|
|
void pre() {
|
|
_Rs = _getResistance();
|
|
}
|
|
|
|
// Descriptive name of the sensor
|
|
String description() {
|
|
return String("MICS-5525 @ TOUT");
|
|
}
|
|
|
|
// Descriptive name of the slot # index
|
|
String slot(unsigned char index) {
|
|
return description();
|
|
};
|
|
|
|
// Address of the sensor (it could be the GPIO or I2C address)
|
|
String address(unsigned char index) {
|
|
return String("0");
|
|
}
|
|
|
|
// Type for slot # index
|
|
unsigned char type(unsigned char index) {
|
|
if (0 == index) return MAGNITUDE_RESISTANCE;
|
|
if (1 == index) return MAGNITUDE_CO;
|
|
return MAGNITUDE_NONE;
|
|
}
|
|
|
|
// Current value for slot # index
|
|
double value(unsigned char index) {
|
|
if (0 == index) return _Rs;
|
|
if (1 == index) return _getPPM();
|
|
return 0;
|
|
}
|
|
|
|
private:
|
|
|
|
unsigned long _getReading() {
|
|
return analogRead(_redGPIO);
|
|
}
|
|
|
|
double _getResistance() {
|
|
|
|
// get voltage (1 == reference) from analog pin
|
|
double voltage = (float) _getReading() / 1024.0;
|
|
|
|
// schematic: 3v3 - Rs - P - Rl - GND
|
|
// V(P) = 3v3 * Rl / (Rs + Rl)
|
|
// Rs = 3v3 * Rl / V(P) - Rl = Rl * ( 3v3 / V(P) - 1)
|
|
// 3V3 voltage is cancelled
|
|
double resistance = (voltage > 0) ? _Rl * ( 1 / voltage - 1 ) : 0;
|
|
|
|
return resistance;
|
|
|
|
}
|
|
|
|
double _getPPM() {
|
|
|
|
// According to the datasheet (https://airqualityegg.wikispaces.com/file/view/mics-5525-CO.pdf)
|
|
|
|
return 764.2976 * fs_pow(2.71828, -7.6389 * ((float) _Rs / _R0));
|
|
|
|
}
|
|
|
|
unsigned long _R0 = MICS5525_R0; // R0, calibration value at 25º on air
|
|
unsigned long _Rl = MICS5525_RL; // RL, load resistance
|
|
unsigned long _Rs = 0; // cached resistance
|
|
unsigned char _redGPIO = MICS5525_RED_PIN;
|
|
|
|
};
|
|
|
|
#endif // SENSOR_SUPPORT && MICS5525_SUPPORT
|