/*
  Arduino | coding-help
  Screen Flicker when updating values

  Syn [puffy], puffy - Tuesday, May 5, 2026 5:26 PM
  Trying to make a custom digital boost/vacuum gauge with a map sensor.
  I finally got the values to be stable but it's causing my SPI screen to flicker.

  Based on:
  https://wokwi.com/projects/307567201804616256
*/

#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_ILI9341.h"

const int TFT_DC =  9;
const int TFT_CS = 10;
const int SENSOR_PIN = A0;

int oldValue = -1; // just so it is never the "raw value" on startup

// Use hardware SPI (on Uno, #13, #12, #11) and the above for CS/DC
Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC);

void setup() {
  Serial.begin(9600);
  Serial.println("ILI9341 Test!");
  tft.begin();
  tft.setTextSize(3);
  tft.setTextColor(ILI9341_GREEN, ILI9341_BLACK);
}

void loop(void) {
  char buffer[8];

  int rawValue = analogRead(SENSOR_PIN);  // read the input pin
  int mappedValue = map(rawValue, 0, 1023, -30, 20);

  if (rawValue != oldValue) {
    oldValue = rawValue;
    Serial.print("Raw value: ");
    Serial.println(rawValue);   // print raw sensor reading

    snprintf(buffer, 8, "%3d", mappedValue);
    tft.setCursor(70, 50);
    tft.print(buffer);
  }
}