Arduino oled display decimal

Other Hardware Displays
1

Hi guys, i ran into some problems with the oled display.
I was trying to make a boost controller for a car with a potentionmeter,
I set the potentionmeter value as max on the display
the map sensor value from the car is correct it's displaying me 0.00
i tried everything to make the "max" value to shown as 0.00 too but with any success

Here is the code:

#include <SPI.h>
#include <Wire.h>
#include <max6675.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define potentiometer A3
#define relay 7
#define alarmr 9
int pottemperature;
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
int rawValue; // A/D readings
int offset = 102; // zero pressure adjust
int fullScale = 922; // max pressure (span) adjust
float pressure; // final pressure




#define OLED_RESET     -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


void setup() {
  Serial.begin(9600);
  Wire.begin();   
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C))
  pinMode(potentiometer, INPUT);
  pinMode(relay, OUTPUT);
  digitalWrite(relay, LOW);
  pinMode(alarmr, OUTPUT);
  digitalWrite(alarmr, LOW);
  display.setTextSize(2);
  display.setTextColor(WHITE);

  updatedisplay();
 }

void loop() {
  rawValue = analogRead(A0);
   pressure = (rawValue - offset) * 3.0 / (fullScale - offset); // conversion
  updatedisplay();
  delay(300);
    if (pressure < pottemperature) {
      digitalWrite(relay, HIGH);
    }
    else if (pressure > pottemperature) {
      digitalWrite(relay , LOW);
      delay(0);
    }
    if (pressure < 1.4 ) {
      digitalWrite(alarmr , HIGH);
    }
    else if (12 > 27) {
     digitalWrite(alarmr , LOW);
    }
  }

 
void zero() {

  }

void updatedisplay() {
  pottemperature = analogRead(potentiometer);
  pottemperature = map(pottemperature, 1, 1023, 0, 1.41);
  display.clearDisplay();
  display.setCursor(15, 20);
  display.print("MAX:");
  display.print(pottemperature, 1);
  display.setCursor(15, 40);
  display.print("BAR:");
  display.print(pressure);
  display.setCursor(5, 0);
  display.print("Levi TURBO");
  display.display();
}

Thanks for any help to make this work, the solenoid control is not done yet, i stopped beacuse of this. The max value what can be set would be 1.40 Bar

2

What is your problem exactly?
The value do not showed in the display at all or it displayed incorrectly or anything else?

3

This code displays the MAX value from the potentionmeter.
I want to display as 0.00
so that i can set it max to 1.40

4

If the problem is that you want to view 2 digits after the point, try this

5

only showing 1 digit, it's doesn't want to put point there, i even tried to put the max value to 1.41 here, but it's only showing max by setting with potentionmeter

pottemperature = map(pottemperature, 1, 1023, 0, 1.41);
6

The map() function can only be used to map integer values, not floats

7

Problem 1: 'pottemperature' is an 'int'. It has no decimal places. To fix it, change to:
float pottemperature;

Problem 2: The 'map()' function only does integers. To fix it, change to:

  pottemperature = analogRead(potentiometer);
  pottemperature = (pottemperature * 1.41) / 1024.0;

Problem 3: You can't specify the number of decimal places to display on an 'int' because it doesn't have any. Fixing Problem 1 will get you 1 decimal place. To get 2, change to:

  display.print("MAX:");
  display.print(pottemperature, 2);

or

  display.print("MAX:");
  display.print(pottemperature);  // 2 places is the defult
8

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