Pins 2,3,4,6,11,12,13 of the AT mega 8 microcontroller are connected to the LCD display via a variable resistor. In the temperature sensor, pins 1, 2 and 3 are GND, DQ and VCC respectively. Pin 14 of the microcontroller is connected directly to pin 2 DQ of the temperature sensor. In the temperature sensor VDC pin 3 is connected to DQ pin 2 via a 4.7k resistor and pin 1 is connected to ground. Pins 15 and 16 of the microcontroller are connected to the buzzer and LED respectively. Figure 3. Wiring diagram with LED and buzzer off When the temperature is above 69, buzzer and LED in flip-flop phase, i.e. LED flashing and buzzer on-off (Figure 3). When the temperature is above 79, the buzzer and LED stay on constantly (Figure 4). Here you can set any temperature. Outside this condition the system continuously displays the engine operating temperature (Figure 5). Figure 4. Circuit diagram with LED and buzzer on flip-flopV status. HARDWARE DEVELOPMENT E