Build Instructions

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• 1

  Medic Mini PCB Edit

  For this build, we reused the Medic Mini circuit but modified the button layout.

  • The tactile push buttons connected to GPIO9 and GPIO19 were removed, since they weren’t needed.
  • The center button, wired to GPIO18, was kept and repurposed as the temperature trigger button.
• 2

  TEMPERATURE SENSOR WIRING

  For wiring, we use four connecting wires.

  • GPIO4 and GPIO5 of the ESP32‑C6 (SDA and SCL) are linked to the I2C pins of the MLX90614 sensor.
  • VCC is connected to the 3.3V pin, and GND goes to ground.

  This completes the basic four‑wire setup needed to power the sensor and enable communication with the Medic Mini board.

• 3

  CODE

  This is the code we prepared for our TempGun Pro, and it's a simple one; let me explain.

  #include <Arduino_GFX_Library.h>
  #include <Wire.h>
  #include <Adafruit_MLX90614.h>
  // --- Pin Definitions for WAVESHARE ESP32-C6 LCD BOARD ---
  #define LCD_MOSI 6
  #define LCD_SCLK 7
  #define LCD_CS 14
  #define LCD_DC 15
  #define LCD_RST 21
  #define LCD_BL 22
  // I2C pins for MLX90614 (as you confirmed they work)
  #define SDA_PIN 4
  #define SCL_PIN 5
  // Button pin
  #define TRIGGER_PIN 18
  // --- Global Objects ---
  // Create an MLX90614 object
  Adafruit_MLX90614 mlx = Adafruit_MLX90614();
  // Create the display objects
  Arduino_DataBus *bus = new Arduino_ESP32SPI(
  LCD_DC, LCD_CS, LCD_SCLK, LCD_MOSI, GFX_NOT_DEFINED
  );
  Arduino_GFX *gfx = new Arduino_ST7789(
  bus, LCD_RST, 2, true, 172, 320, 34, 0, 34, 0
  );
  // --- State and Timing Variables ---
  enum GunState {
  READY,
  MEASURING,
  DISPLAY_RESULT
  };
  GunState currentState = READY;
  unsigned long lastMeasurementTime = 0;
  const unsigned long resultDisplayTime = 5000; // Display result for 5 seconds
  // Button debouncing
  bool lastButtonState = HIGH;
  unsigned long lastDebounceTime = 0;
  const unsigned long debounceDelay = 50;
  // --- Drawing Functions ---
  void drawReadyScreen() {
  gfx->fillScreen(BLACK);
  // Draw the crosshair
  int centerX = gfx->width() / 2;   // Center of 320px width
  int centerY = gfx->height() / 2;  // Center of 172px height
  gfx->drawCircle(centerX, centerY, 30, WHITE);
  gfx->drawFastHLine(centerX - 40, centerY, 80, WHITE);
  gfx->drawFastVLine(centerX, centerY - 40, 80, WHITE);
  gfx->drawCircle(centerX, centerY, 5, RED);
  gfx->fillCircle(centerX, centerY, 2, RED);
  // --- Draw "TempGun Pro" title ---
  int16_t x1, y1;
  uint16_t w, h;
  // Draw "TempGun"
  gfx->setTextSize(4);
  gfx->setTextColor(RED);
  gfx->getTextBounds("TempGun", 0, 0, &x1, &y1, &w, &h);
  int tempgun_y = 35;
  gfx->setCursor((gfx->width() - w) / 2, tempgun_y);
  gfx->print("TempGun");
  // Draw "PRO" below it, slightly bigger
  gfx->setTextSize(5); // Slightly bigger
  gfx->getTextBounds("PRO", 0, 0, &x1, &y1, &w, &h);
  int pro_y = tempgun_y + h + 2; // Position below "TempGun"
  gfx->setCursor((gfx->width() - w) / 2, pro_y);
  gfx->println("PRO");
  // --- Draw instruction text ---
  gfx->setTextSize(1);
  gfx->setTextColor(WHITE);
  gfx->getTextBounds("Press button to measure", 0, 0, &x1, &y1, &w, &h);
  gfx->setCursor((gfx->width() - w) / 2, gfx->height() - 15);
  gfx->println("Press button to measure");
  }
  void drawMeasuringScreen() {
  // Redraw crosshair in red to indicate scanning
  int centerX = gfx->width() / 2;
  int centerY = gfx->height() / 2;
  gfx->drawCircle(centerX, centerY, 30, RED);
  gfx->drawFastHLine(centerX - 40, centerY, 80, RED);
  gfx->drawFastVLine(centerX, centerY - 40, 80, RED);
  // Clear the old text and write new text
  int16_t x1, y1;
  uint16_t w, h;
  gfx->setTextSize(1);
  gfx->setTextColor(ORANGE);
  gfx->getTextBounds("SCANNING...", 0, 0, &x1, &y1, &w, &h);
  gfx->fillRect(0, gfx->height() - 15, gfx->width(), h + 5, BLACK);
  gfx->setCursor((gfx->width() - w) / 2, gfx->height() - 15);
  gfx->println("SCANNING...");
  }
  void drawResultScreen(float objTemp, float ambTemp) {
  gfx->fillScreen(BLACK);
  // --- Draw "TempGun Pro" title ---
  int16_t x1, y1;
  uint16_t w, h;
  // Draw "TempGun"
  gfx->setTextSize(3);
  gfx->setTextColor(ORANGE);
  gfx->getTextBounds("TempGun", 0, 0, &x1, &y1, &w, &h);
  int tempgun_y = 25;
  gfx->setCursor((gfx->width() - w) / 2, tempgun_y);
  gfx->print("TempGun");
  // Draw "PRO" below it, slightly bigger
  gfx->setTextSize(4); // Slightly bigger
  gfx->getTextBounds("PRO", 0, 0, &x1, &y1, &w, &h);
  int pro_y = tempgun_y + h + 2; // Position below "TempGun"
  gfx->setCursor((gfx->width() - w) / 2, pro_y);
  gfx->println("PRO");
  // --- Adjusted Temperature Values Layout ---
  int label_y = 100; // Shifted down from 80
  int value_y_c = label_y + 15; // Position for Celsius value
  int value_y_f = value_y_c + 55; // Position for Fahrenheit value
  int ambient_label_y = value_y_f + 40; // Position for Ambient label
  int ambient_value_y = ambient_label_y + 15; // Position for Ambient value
  // Object Temperature
  gfx->setTextSize(1);
  gfx->setTextColor(WHITE);
  gfx->setCursor(10, label_y);
  gfx->println("Object:");
  gfx->setTextSize(4);
  gfx->setTextColor(RED);
  gfx->setCursor(10, value_y_c);
  gfx->print(objTemp, 1);
  gfx->println(" C");
  // Fahrenheit conversion
  gfx->setTextSize(2);
  gfx->setTextColor(ORANGE);
  gfx->setCursor(10, value_y_f);
  gfx->print((objTemp * 9.0 / 5.0) + 32.0, 1);
  gfx->println(" F");
  // Ambient Temperature
  gfx->setTextSize(1);
  gfx->setTextColor(WHITE);
  gfx->setCursor(10, ambient_label_y);
  gfx->println("Ambient:");
  gfx->setTextSize(2);
  gfx->setTextColor(GREEN);
  gfx->setCursor(10, ambient_value_y);
  gfx->print(ambTemp, 1);
  gfx->println(" C");
  }
  void drawSensorErrorScreen() {
  gfx->fillScreen(BLACK);
  gfx->setCursor(10, 80);
  gfx->setTextSize(2);
  gfx->setTextColor(RED);
  gfx->println("Sensor Error!");
  gfx->setCursor(10, 110);
  gfx->println("Check wiring &");
  gfx->setCursor(10, 140);
  gfx->println("I2C address.");
  }
  // --- Main Arduino Functions ---
  void setup() {
  Serial.begin(115200);
  delay(1000);
  Serial.println("SETUP: Starting...");
  Wire.begin(SDA_PIN, SCL_PIN);
  Serial.println("SETUP: Finding MLX90614 sensor...");
  if (!mlx.begin()) {
  Serial.println("SETUP: ERROR - Failed to find MLX90614 sensor.");
  pinMode(LCD_BL, OUTPUT);
  digitalWrite(LCD_BL, HIGH);
  gfx->begin();
  drawSensorErrorScreen();
  while (1);
  }
  Serial.println("SETUP: MLX90614 sensor found.");
  Serial.println("SETUP: Initializing Display...");
  pinMode(LCD_BL, OUTPUT);
  digitalWrite(LCD_BL, HIGH);
  gfx->begin();
  Serial.println("SETUP: Display initialized.");
  pinMode(TRIGGER_PIN, INPUT_PULLUP);
  Serial.println("SETUP: Button initialized.");
  Serial.println("SETUP: Drawing ready screen.");
  drawReadyScreen();
  Serial.println("SETUP: Complete. Starting loop.");
  }
  void loop() {
  static unsigned long lastHeartbeat = 0;
  if (millis() - lastHeartbeat > 5000) {
  Serial.println("LOOP: Heartbeat - loop is running.");
  lastHeartbeat = millis();
  }
  int reading = digitalRead(TRIGGER_PIN);
  if (reading != lastButtonState) {
  lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > debounceDelay) {
  if (reading == LOW && currentState == READY) {
  Serial.println("LOOP: Button pressed. Starting measurement.");
  currentState = MEASURING;
  lastMeasurementTime = millis();
  drawMeasuringScreen();
  }
  }
  lastButtonState = reading;
  switch (currentState) {
  case READY:
  break;
  case MEASURING:
  if (millis() - lastMeasurementTime > 500) {
  Serial.println("LOOP: Taking temperature reading...");
  float objectTemp = mlx.readObjectTempC();
  float ambientTemp = mlx.readAmbientTempC();
  Serial.print("LOOP: Object Temp: "); Serial.print(objectTemp); Serial.println(" C");
  Serial.print("LOOP: Ambient Temp: "); Serial.print(ambientTemp); Serial.println(" C");
  drawResultScreen(objectTemp, ambientTemp);
  currentState = DISPLAY_RESULT;
  lastMeasurementTime = millis();
  }
  break;
  case DISPLAY_RESULT:
  if (millis() - lastMeasurementTime > resultDisplayTime) {
  Serial.println("LOOP: Result display timeout. Returning to ready.");
  currentState = READY;
  drawReadyScreen();
  }
  break;
  }
  }
  

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