I just successfully set up an Arduino to monitor three NTC thermistors and to control a pump and a fan using a relay board. When writing the code (by borrowing from Adafruit NTC thermistor code), I was wondering if there is a better way, by using variables, to shorten it. Any ideas?
// SPDX-FileCopyrightText: 2011 Limor Fried/ladyada for Adafruit Industries
//
// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2011 Limor Fried/ladyada for Adafruit Industries
//
// SPDX-License-Identifier: MIT
// Thermistor Example #3 from the Adafruit Learning System guide on Thermistors
// https://learn.adafruit.com/thermistor/overview by Limor Fried, Adafruit Industries
// MIT License - please keep attribution and consider buying parts from Adafruit
#include <SPI.h>
// which analog pin to connect
#define oATemp A0
#define supplyTemp A1
#define returnTemp A2
#define fanControl 0 // Arduino pin connected to relay for fan
#define pumpControl 1 // Arduino pin connected to relayfor pump
// resistance at 25 degrees C
#define THERMISTORNOMINAL 10000
// temp. for nominal resistance (almost always 25 C)
#define TEMPERATURENOMINAL 25
// how many samples to take and average, more takes longer
// but is more 'smooth'
#define NUMSAMPLES 5
// The beta coefficient of the thermistor (usually 3000-4000)
#define BCOEFFICIENT 3950
// the value of the 'other' resistor
#define SERIESRESISTOR 10000
int samples[NUMSAMPLES];
const int AIR_TEMP_THRESHOLD_UPPER = 74; // Start fan to circulate warm air around barrels, change to your desire value
const int AIR_TEMP_THRESHOLD_LOWER = 65; // Stop fan to prevent cooling barrels, change to your desire value
const int WATER_TEMP_THRESHOLD_UPPER = 50; // Start pump to heat greenhouse floor, change to your desire value
const int WATER_TEMP_THRESHOLD_LOWER = 40; // Stop pump to prevent cooling greenhouse floor, change to your desire value
void setup(void) {
Serial.begin(9600);
pinMode(oATemp, INPUT);
pinMode(supplyTemp, INPUT);
pinMode(returnTemp, INPUT);
pinMode(fanControl, OUTPUT);
pinMode(pumpControl, OUTPUT);
}
void loop(void) {
uint8_t i;
float average;
// take N samples in a row, with a slight delay
for (i=0; i< NUMSAMPLES; i++) {
samples[i] = analogRead(oATemp);
delay(10);
}
// average all the samples out
average = 0;
for (i=0; i< NUMSAMPLES; i++) {
average += samples[i];
}
average /= NUMSAMPLES;
// convert the value to resistance
average = 1023 / average - 1;
average = SERIESRESISTOR / average;
float oATemp;
oATemp = average / THERMISTORNOMINAL; // (R/Ro)
oATemp = log(oATemp); // ln(R/Ro)
oATemp /= BCOEFFICIENT; // 1/B * ln(R/Ro)
oATemp += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
oATemp = 1.0 / oATemp; // Invert
oATemp -= 273.15; // convert absolute temp to C
oATemp = oATemp *1.8+32;
{
if (oATemp > AIR_TEMP_THRESHOLD_UPPER) {
Serial.println("Fan relay is turned on");
digitalWrite(fanControl, HIGH); // turn on
} else if (oATemp < AIR_TEMP_THRESHOLD_LOWER) {
Serial.println("Fan relay is turned off");
digitalWrite(fanControl, LOW); // turn off
}
Serial.print("Outdoor Air Temperature ");
Serial.print(oATemp);
Serial.println(" DegF");
delay(1000);
uint8_t j;
float average1;
// take N samples in a row, with a slight delay
for (j=0; j< NUMSAMPLES; j++) {
samples[j] = analogRead(supplyTemp);
delay(10);
}
// average all the samples out
average = 0;
for (j=0; j< NUMSAMPLES; j++) {
average += samples[j];
}
average /= NUMSAMPLES;
// convert the value to resistance
average = 1023 / average - 1;
average = SERIESRESISTOR / average;
float supplyTemp;
supplyTemp = average / THERMISTORNOMINAL; // (R/Ro)
supplyTemp = log(supplyTemp); // ln(R/Ro)
supplyTemp /= BCOEFFICIENT; // 1/B * ln(R/Ro)
supplyTemp += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
supplyTemp = 1.0 / supplyTemp; // Invert
supplyTemp -= 273.15; // convert absolute temp to C
supplyTemp = supplyTemp *1.8+32;
Serial.print("Supply Temperature ");
Serial.print(supplyTemp);
Serial.println(" DegF");
delay(1000);
uint8_t k;
float average2;
// take N samples in a row, with a slight delay
for (k=0; k< NUMSAMPLES; k++) {
samples[k] = analogRead(returnTemp);
delay(10);
}
// average all the samples out
average = 0;
for (k=0; k< NUMSAMPLES; k++) {
average += samples[k];
}
average /= NUMSAMPLES;
// convert the value to resistance
average = 1023 / average - 1;
average = SERIESRESISTOR / average;
float returnTemp;
returnTemp = average / THERMISTORNOMINAL; // (R/Ro)
returnTemp = log(returnTemp); // ln(R/Ro)
returnTemp /= BCOEFFICIENT; // 1/B * ln(R/Ro)
returnTemp += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
returnTemp = 1.0 / returnTemp; // Invert
returnTemp -= 273.15; // convert absolute temp to C
returnTemp = returnTemp *1.8+32;
{
if (returnTemp > WATER_TEMP_THRESHOLD_UPPER) {
Serial.println("Pump relay is turned on");
digitalWrite(pumpControl, HIGH); // turn on
} else if (returnTemp < WATER_TEMP_THRESHOLD_LOWER) {
Serial.println("Pump relay is turned off");
digitalWrite(pumpControl, LOW); // turn off
}
Serial.print("Return Temperature ");
Serial.print(returnTemp);
Serial.println(" DegF");
delay(1000);
}
}
}
