Electric ceramic stove development

Using STC15w402as-sop16-pin microcontroller

Functional flow: The power-on buzzer beeps once, indicating that the power is on. Press the rotary encoder switch to turn on the machine, the buzzer will sound long, the fan will rotate, and the load adjustment power is 0. The user turns the rotary encoder clockwise to increase the power and counterclockwise to decrease it. Press the rotary encoder switch again to shut down, the buzzer will sound for a long time, and the fan will stop after a few minutes delay. If it is turned on and the furnace surface temperature reaches 500°C during heating, it will be forced to shut down, and the fan delay time will be the same as the normal shutdown time. Whether the main power is turned off or the main power is turned on and off for the nth time, the process is consistent with the above.
Note: The fan delay time is the same after the user shuts down the machine and the temperature reaches 500°C.