Problem with delay()

Projects Programming
1

Hi!
I'm writing a code for my project and I noticed some really weird stuff! Basically if I want to use delay function in my code for some reason I need to write the value which is 100 bigger to get the desired delay! So if I want five seconds delay then I need to write delay(500 000) and not delay(5000), even after this I get 8,20s delay???

My guess is that this happens because I use hardware interrupts in my code but how can I use interrupts and delay at the same time?

Here is my code:

#include <SPI.h>
#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_ST7735.h> // Hardware-specific library

// For the breakout, you can use any (4 or) 5 pins
#define sclk 52 //13 //52
#define mosi 51//11 //51
#define cs   53//10 //53
#define dc   9  
#define rst  8  // you can also connect this to the Arduino reset

// Option 1: use any pins but a little slower
//Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, mosi, sclk, rst);
Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, rst);
// Counts number of button presses
// output count to serial
// blink a led according to count
#define BUTTON1_PIN        2           //seöect switch 
const unsigned int DEBOUNCE_TIME = 200;
const unsigned int REFRESH_TIME = 300;
byte buttonInterrupt = 0;
unsigned int counter = 0;
static unsigned long last_interrupt_time = 0;

byte switchPin1 = 18;                  // switch 1 +
byte switchPin2 = 19;                  // switch 2 -         

byte buttonPresses = 0;                // how many times the button has been pressed 
byte lastPressCount = 0;               // to keep track of last press count


byte mainmenu=0;
byte phmenucount=0;
byte phcal = 0;


void setup() { //*************************************SETUP*****************************************************************
 Serial.begin(9600);                 // Set up serial communication at 9600bps


  pinMode(BUTTON1_PIN, INPUT);
  digitalWrite(BUTTON1_PIN, HIGH);     // Set the switch pin as input
  attachInterrupt(0, button1, FALLING); //interrupt
    
  pinMode(switchPin1, INPUT);          // Set the switch pin as input
  digitalWrite(switchPin1, HIGH);      // set pullup resistor
 
  pinMode(switchPin2, INPUT);          // Set the switch pin as input
  digitalWrite(switchPin2, HIGH);      // set pullup resistor
 
  tft.initR(INITR_BLACKTAB);   // initialize a ST7735S chip, black tab
    Serial.println("init");

 }

void loop(){  //*************************************LOOP*****************************************************************
 

  

switch (mainmenu) {  
         case 1:
            if (digitalRead(switchPin1) == LOW)  // check if button was pressed
             {
              buttonPresses++;                  // increment buttonPresses count
              delay(500);                       // debounce switch
            }
              if (digitalRead(switchPin2) == LOW)  // check if button was pressed
            {
             buttonPresses--;                  // increment buttonPresses count
             delay(500);                       // debounce switch
            }
  
            if (buttonPresses == 6) buttonPresses = 1;     
            if (buttonPresses == 0) buttonPresses = 5;   // rollover every fourth press
            if (lastPressCount != buttonPresses)              // only do output if the count has changed
            {
              Serial.print ("Main menu count: ");          // out to serial
              Serial.println(buttonPresses, DEC);
     
             lastPressCount = buttonPresses;    // track last press count
            }  
             
        break; 
  }  
}  
void phcalwindow(){
tft.fillScreen(ST7735_BLACK);
  tft.setTextColor(ST7735_GREEN);
  tft.setCursor(3, 2);
  tft.setTextSize(2);
  tft.print("pH ");
  tft.setCursor(30, 10);
  tft.setTextSize(1);
  tft.print(" Calibration");
  delay (500000);               //<<<<<<<<< this is the delay!!!!!!!!!!!!
  tft.print(" Done!");
  
}
void eccalwindow(){
tft.fillScreen(ST7735_BLACK);
  tft.setTextColor(ST7735_GREEN);
  tft.setCursor(1, 140);
  tft.print("EC Calibration");
}
 void otherwindow(){
tft.fillScreen(ST7735_BLACK);
  tft.setTextColor(ST7735_GREEN);
  tft.setCursor(1, 140);
  tft.print("Other stuff");
}
void infowindow(){
tft.fillScreen(ST7735_BLACK);
  tft.setTextColor(ST7735_GREEN);
  tft.setCursor(1, 140);
  tft.print("Info");
}
  
void button1(){   //*************************************BUTTON1*****************************************************************
unsigned long interrupt_time = millis();
if (interrupt_time - last_interrupt_time > DEBOUNCE_TIME) {
  Serial.println("Button 1 (Select)");  

            if(buttonPresses == 0) {
            Serial.println ("Show menu window"); 
            buttonPresses = 6;
            mainmenu = 1; 
            }

            if(buttonPresses  == 1){ 
            Serial.println ("pH cal start"); 
            phcalwindow();
             mainmenu = 0; 
            
            }

            if(buttonPresses  == 2){ 
            Serial.println ("EC cal start"); 
             mainmenu = 0; 
            }

            if(buttonPresses  == 4){ 
            Serial.println ("Other"); 
             mainmenu = 0; 
            }
            if(buttonPresses  == 5){
            Serial.println ("Exit to main window"); 
            delay(100);
             mainmenu = 0; 
             buttonPresses = 0;
             
            }

}
last_interrupt_time = interrupt_time;  
}

Any help would be much appreciated!

2

delay() does not work inside an ISR
Serial.print() uses interrupts.
Interrupts are automatically disabled when in an ISR.
You have delay() and Serial.print() in your ISR

Do you think that there might be a problem ?

3 
            if (digitalRead(switchPin1) == LOW)  // check if button was pressed
             {
              buttonPresses++;                  // increment buttonPresses count
              delay(500);                       // debounce switch
            }
              if (digitalRead(switchPin2) == LOW)  // check if button was pressed
            {
             buttonPresses--;                  // increment buttonPresses count
             delay(500);                       // debounce switch
            }

Wrong. You should be incrementing or decrementing when the switch BECOMES pressed, not IS pressed. Look at the state change detection example.

It takes nowhere near half a second to debounce a switch.

              Serial.print ("Main menu count: ");          // out to serial

Really? Without that comment, I'd have never known. 8)

A switch statement with one case looks pretty stupid. A simple if statement is far clearer.

Your indenting
sucks big time. There
is a reason that the
Tools menu has a Auto Format item. Learn
why it's there.

Plus, of course, what UKHeliBob says.

4

UKHeliBob:
delay() does not work inside an ISR
Serial.print() uses interrupts.
Interrupts are automatically disabled when in an ISR.
You have delay() and Serial.print() in your ISR

Do you think that there might be a problem ?

Yep! That was the problem, thanks for helping!

PaulS:
The switch works fine so I think there is no reason to change anything there but thanks for your opinion! I forgot to comment that there will be more than one case in the switch statement. 8)
..and thanks for pointing out the Auto Format tool, than makes everything look really nice!

5

delay is bad beginner habbit better use millis() more code but program does not holdup