This control system has two modes:- 1- Automatic Control 2- Manual Control
The fan speed is determined based on the room temperature(T). The temperature is calculated from a sensor temperature readings called LM35. The sensor is connected with the microcontroller on AN A/D channel pin and convert the analog readings to digital values values using the ADC module inside the MCU. There is 3 speed levels 1, 2, 3. They are implemented using the CCP1 module inside the MCU. There are 4 cases: 1- If (T < 18) => The fan speed will be 0 automatically. 2- If (18 <= T < 25) => The fan speed will be 1 automatically. 3- If (25 <= T < 35) => The fan speed will be 2 automatically. 4- If (T >= 35) => The fan speed will be 3 automatically.
The user select the fan speed whatever the temperature is. It also has 3 speed levels 1, 2, 3.
This system is able to save the last mode choosen by the user before going to reset. This is done by saving the control_mode variable in the first location in the EEPROM. User must press ## '1' on the keypad to select Automatic mode and ## '2' to select Manual mode. In Manual mode, press '1' => speed level 1 '2' => speed level 2 '3' => speed level 3 '4' => turn fan off In both modes, Press ## '0' to return to the main menu and select the the control mode.