I need help to replace delay() with millis() function

Using Arduino Programming Questions
1

This is the very first time i'm programming on arduino. Basically my project is about reading temperature of avr cpu with adc and then blink some leds. For instance if temp is let's say 35, i'll have 35 on my monitor, and a red led blink 3 times and a blue led who will blink 5 times; and if temp gets over 80 a yellow led will start blinking.
All this runs with timer1 with 1024 prescaler, and im using registers to setup and blink leds.
My problem is that the temp i get on monitor is not updated together with the temp that the leds blink. For example, temp is 27,on monitor i get 27, led blink 27 then after 4 seconds when timer1 ends temp is 28, led blink 28 but i get no 28 on screen. And this happens for some of the starting temperatures, after 4 or 5 temperatures they will finally be updated together. And im wondering why is this happening and i thought it could be because im using delay() so i wanted to see if anything changed by using millis() instead.

i know i should do something like this

void setup()
{
  Serial.begin(115200);  //start Serial in case we need to print debugging info
  pinMode(ledPin, OUTPUT);
  startMillis = millis();  //initial start time
}

void loop()
{
  currentMillis = millis();  //get the current "time" (actually the number of milliseconds since the program started)
  if (currentMillis - startMillis >= period)  //test whether the period has elapsed
  {
    digitalWrite(ledPin, !digitalRead(ledPin));  //if so, change the state of the LED.  Uses a neat trick to change the state
    startMillis = currentMillis;  //IMPORTANT to save the start time of the current LED state.
  }
}

but i cant make it work with registers instead of digitalWrite/digitalRead
this is the code where i need to use millis() instead of delay
if anyone can give me some example code that would work in a for cycle using registers i would be very grateful

float offset=293.51;
float gain= 0.99;

void setup() {
  TCCR1A = 0;
  TCCR1B = 0;
  TCCR1B=B00000101;
  TIMSK1=B00000001; // attivo timer overflow interrupt
  Serial.begin(9600); //stampo a monitor
  DDRB=B11010000; // pin 12 in output
  DDRD=B11110000; // pin 7 e 6 in output
  ADMUX = 0b11001000; //metto a 1 REFS1,REFS0 e MUX3 per avere il confronto interno con 1.1V 
  ADCSRA= 0b10000111; // metto a 1 ADPS0, ADPS1, ADPS2 e ADEN per far partire la conversione
}

ISR(TIMER1_OVF_vect) {
  ADCSRA |= 0b1000000; // metto a 1 ADSC per far partire l'ADC
  while(ADCSRA & 0b1000000); // coverto...
  int aRead= ADCL;
  aRead |= (ADCH << 8);
  float t= (((aRead)-offset)/gain); //  converto e calibro la temperatura in gradi celsius
  Serial.println(t);
  checkTemp(t);
}

void loop(){
}

//////////////////////////////////
void ledBlink(int t){
    int tempDecine=t/10;
  for(int i=0;i<tempDecine;i++){
    PORTD=B10000000;
    delay(350);
    PORTD=B00000000;
    delay(350);
  }
delay(350);
int tempUnita=t;
while (tempUnita>10){
  tempUnita= tempUnita-10;
  if (tempUnita==10){
    tempUnita=0;
  }}
for (int i=0;i<tempUnita;i++){
    PORTB=B11010000;
    delay(350);
    PORTB=B11000000;
    delay(350);
}
  delay(3000);

}

void checkTemp(int t){
    if(t>=80){
    PORTD=B01000000;
    delay(350);
    PORTD=B00000000;
    delay(350);
}else{
  ledBlink(t);
}
}
2

Unless you're fiddling around with the timer that runs micros/millis, there should be no reason port register manipulation doesn't work just as well as using digitalRead/Write

Please remember to use code tags when posting code

3

Please, post complete sketch with code tags (</>).

4

I think your guess is wrong. It's tempting to fish for a way out of a problem, but this is really a far fetched attempt at a solution. It's far more likely that your code has some built in problem. What did you see that made you think it was a timing problem? It could be because of delay() but it could equally likely be caused by billions of possible other things.

5

@stracciatellaxd, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project :wink: See About the Installation & Troubleshooting category.

6

@stracciatellaxd's current code

float offset = 293.51;
float gain = 0.99;

void setup() {
  TCCR1A = 0;
  TCCR1B = 0;
  TCCR1B = B00000101;
  TIMSK1 = B00000001; // attivo timer overflow interrupt
  Serial.begin(9600); //stampo a monitor
  DDRB = B11010000; // pin 12 in output
  DDRD = B11110000; // pin 7 e 6 in output
  ADMUX = 0b11001000; //metto a 1 REFS1,REFS0 e MUX3 per avere il confronto interno con 1.1V
  ADCSRA = 0b10000111; // metto a 1 ADPS0, ADPS1, ADPS2 e ADEN per far partire la conversione
}

ISR(TIMER1_OVF_vect) {
  ADCSRA |= 0b1000000; // metto a 1 ADSC per far partire l'ADC
  while (ADCSRA & 0b1000000); // coverto...
  int aRead = ADCL;
  aRead |= (ADCH << 8);
  float t = (((aRead) - offset) / gain); //  converto e calibro la temperatura in gradi celsius
  Serial.println(t);
  checkTemp(t);
}

void loop() {
}

//////////////////////////////////
void ledBlink(int t) {
  int tempDecine = t / 10;
  for (int i = 0; i < tempDecine; i++) {
    PORTD = B10000000;
    delay(350);
    PORTD = B00000000;
    delay(350);
  }
  delay(350);
  int tempUnita = t;
  while (tempUnita > 10) {
    tempUnita = tempUnita - 10;
    if (tempUnita == 10) {
      tempUnita = 0;
    }
  }
  for (int i = 0; i < tempUnita; i++) {
    PORTB = B11010000;
    delay(350);
    PORTB = B11000000;
    delay(350);
  }
  delay(3000);

}

void checkTemp(int t) {
  if (t >= 80) {
    PORTD = B01000000;
    delay(350);
    PORTD = B00000000;
    delay(350);
  } else {
    ledBlink(t);
  }
}

Note:
It's not advisable to use Serial.print in an ISR. And the bigger problem is the use of delay() in the ISR (indirectly).

7

Thanks for your answer, I am also new to this forum so I apologize for not using the right format for the code.

I have to use port registers because my professor wants it that way.
I find really hard to translate the function digitalRead to something with port registers. How can i return an output pin status (high or low) using registers?

8

Usually, an output pin's state will be the last thing you wrote to it, unless you have some internal hardware like a UART writing to it.

9

Thanks for your answer, I am also new to this forum so I apologize for not using the right format for the code.

If serial print isnt recommended, Is there anything else I can do to show my temperature on screen?

10

I know that but I cant figure the code that would return that status to me

11

But you wrote it - just keep a copy

12

I thought so because it worked perfectly fine before being attached to an isr

13

I need it to be with registers though, is there a way to do it without using digitalRead?

14

You can use PORT.

15

If you're not supposed to using digitalRead/Write, why are you using Serial?

16

PORT makes pins low or high, how do i use it to return a pin status?

17

cause I don't know any other way to print my temperature on screen

18

PIN for reading.

19

PIN reads state of input pins, not my case since they re output

20 
ISR(TIMER1_OVF_vect) {
  ADCSRA |= 0b1000000; // metto a 1 ADSC per far partire l'ADC
  while (ADCSRA & 0b1000000); // coverto...
  int aRead = ADCL;
  aRead |= (ADCH << 8);
  float t = (((aRead) - offset) / gain); //  converto e calibro la temperatura in gradi celsius
  Serial.println(t);
  checkTemp(t);
}

This TIMER1_OVF_vect ISR is wrong for several reasons as pointed out by @ sterretje in post #4.

You would do better to only set a flag =true in the ISR and then respond to that flag in loop().