Hello there,
I am currently trying to build some sort of weather-station with a simple dual relay module attached to it
in order to toggle a fan and a mister independently.
I also managed to add a small 1.8-inch TFT display which shows the current readings from a DHT11 sensor.
The number in red shows the runtime of the Arduino Nano (in millis), mostly for debugging.
Here is what I want it to do: IF the humidity reading exceeds a value of 75%
THEN run the fan for 10 Minutes (close circuit on relay 1)
Note: It is likely that the humidity drops below the 75% threshold very shortly after the fan has been activated.
That is why I need it to run for a set amount of time. It didn't take long to understand that the delay (); - function wasn't the right choice here since I want to monitor the sensor values during ventilation- or misting times as well. I have spent quite some time reading up on the millis(); - function and how to set up a timer-counter but i have trouble understanding on how to implement this into the control logic - part of my code.
#include <SPI.h>
#include "Ucglib.h"
#include <dht.h>
dht DHT;
#define DHT11_PIN 4 // defines Signal Pin for the Sensor on the Nano
Ucglib_ST7735_18x128x160_HWSPI ucg(/*cd=*/ 9, /*cs=*/ 10, /*reset=*/ 8); // Correct Driver for ST7735 Display + Pin-Layout on the Nano
const int relayPin = 3; // defines Signal Pin for the Relay
unsigned long previoustime_1 = 1001; // initial value for timestamp is 0; this should get updated during the loop, I guess ...
const unsigned long fantime = 10000; // constant value for a variable called "fantime" = 10000ms or 10 seconds
void setup(void) ///////////////////////////////////SETUP//////////////////////////////////////////////
{
delay(1000);
//Relay Setup
pinMode(relayPin, OUTPUT); // sets the mode of the pin to output
//Display Setup // rotates the Display into "portrait-mode" and clears it once at the beginning
ucg.begin(UCG_FONT_MODE_TRANSPARENT);
ucg.setRotate180();
ucg.undoClipRange();
ucg.clearScreen();
//Outer Frame // this draws all static graphics (Labels, Borders, etc,)
//ucg.setColor(0, 111, 255); //draw orange (alternative color)
ucg.setColor(255, 255, 255); //draw white
ucg.drawLine(0, 0, 125, 0); //top line
ucg.drawLine(0, 18, 125, 18); //second top line
ucg.drawLine(0, 0, 0, 160); //left colum
ucg.drawLine(125, 0, 125, 160); //right colum
ucg.drawLine(0, 158, 125, 158); //bottom line
//Inner Frame
ucg.drawLine(65, 18, 65, 65); // middle colum
ucg.drawLine(0, 65, 125, 65); // upper divider
ucg.drawLine(0, 100, 125, 100); //lower divider
//Static Text
ucg.setFont(ucg_font_profont15_8f); // Device Name & Version
ucg.setColor(255, 255, 255);
ucg.setPrintPos(11,13 );
ucg.print("Greenhouse V0.1");
//Static Text Climate controlers (circut on relay 1(fan) & circut on relay 2(mister)
ucg.setFontMode(UCG_FONT_MODE_SOLID);
ucg.setFont(ucg_font_profont15_8f);
ucg.setPrintPos(11, 80);
ucg.print("Fan");
ucg.setPrintPos(11, 95);
ucg.print("Mister");
}
void loop(void) //////////////////LOOP/////////////////////////////////////////////
{
//Runtime on display (for debugging)
unsigned long currenttime = millis();
ucg.setFont(ucg_font_inb16_mf);
ucg.setPrintPos(10, 135);
ucg.setColor(0,0, 255); // draw red
ucg.print(currenttime);
//Sensor check value pin
int chk = DHT.read11(DHT11_PIN); // DHT11 Sensor can now be read
//Control Logic
if(DHT.humidity > 75)
{
digitalWrite(relayPin, LOW); // ??????????? How do I time this correctly???????????
}
else
digitalWrite(relayPin, HIGH);
I have defined a variable to keep track of the time (elapsed millis) and a constant value for the fan runtime (set to 10 sec for debugging).
How do I implement this correctly? Do I need to build it via an While-statement inside of an If-statement?
I cannot wrap my head around this for some reason. Please, someone help me understand :o
