Can't get it to hold max temp.

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1

I'm pretty new about coding, I've read a lot of forum threads and tried for several days, but I can not get it to hold "maxtemp" until I press the reset button, max temp dropping with temp, and I need that continues to show what max temp has been

The button is connected to + 5V on one side and the other side has a 1k ohm resistor to 0V, and at the same legs as the button modstenden is connected to a wire to pin 13 on my Arduino uno.

#include <LiquidCrystal.h>
#include <max6675.h>

// setup termocupler
int thermoDO = 8;
int thermoCS_1 = 10;
int thermoCLK = 9;
MAX6675 thermocouple_1(thermoCLK, thermoCS_1, thermoDO);

float temp;
float maxtemp = 0;

// setup lcd
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);

// setup button 

const int buttonPin = 13;
int buttonState = 0;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  lcd.begin(20, 4);
  // wait for MAX chip to stabilize
  delay(500);
  pinMode(buttonPin,INPUT_PULLUP);
}

void loop() {  
 
// Temp read

Serial.print("Sensor_1 temp = "); 
   Serial.println(thermocouple_1.readCelsius());
  temp = thermocouple_1.readCelsius();

// Read maxtemp

  if (temp > maxtemp) maxtemp = temp;

Serial.print("maxtemp       = ");
  Serial.println(maxtemp);



// Wright lcd   

   lcd.clear();
   lcd.setCursor(0,0);
   lcd.print("EGT Temp ");
   lcd.print(temp);

   lcd.setCursor(0,2);
   lcd.print("MAX Temp ");
   lcd.print(maxtemp);
   delay(500);


//Button

buttonState = digitalRead(buttonPin);

if (buttonState == LOW) {
    // reset maxtemp
    maxtemp = 0;
}  
}

Hope you guys can help me.

2

brunokc:
The button is connected to + 5V on one side and the other side has a 1k ohm resistor to 0V, and at the same legs as the button modstenden is connected to a wire to pin 13 on my Arduino uno.

Since you have the button connected to 5V, you should change the line:

if (buttonState == LOW) {

to

if (buttonState == HIGH) {

The problem is the button was constantly being read as pressed so maxtemp is set to 0 on every loop.

brunokc:

  pinMode(buttonPin,INPUT_PULLUP);

Not related to your problem but if you have a pull down resistor on pin 13(the 1k ohm resistor to 0V) then there's no point in setting the pin mode to INPUT_PULLUP, you should use INPUT instead. Alternately you could get rid of the 1K resistor and wire the button to ground instead of 5V and reverse your button logic(active LOW).

3

Thanks you many times ....

my head was about to explode :smiley:

Thanks thanks thanks thanks....