T12 Soldering Iron Driver Board

The circuit structure is simple, and the program is even simpler; it's actually a practice project I made a long time ago. However, it's functionally quite good and has been working without problems until now. It's more than capable of soldering common components.
The Arduino source code has been uploaded.
 
Functions:
1. Press the switch to turn it on.
2. There are two knobs in the circuit. The larger knob is used to adjust the set temperature, with a default adjustment range of 75-375°C. The smaller knob (blue 3296W) is used to calibrate the temperature measurement.
3. The program has automatic sleep and automatic wake-up functions, but these are generally not needed. It is recommended to lift the switch to turn it off when not in use.
4. Red and green LEDs are used to indicate the status. When the red light is on (it may be red or yellow), the digital display shows the set temperature; when the red light is off (it may be green or completely off), the digital display shows the actual temperature of the soldering iron tip. A green light indicates that the soldering iron tip is heating.
5. If the digital display shows Err, it means the soldering iron tip is not inserted or there is poor contact.
 
Precautions:
1. The six-pin push-button switch has left and right sides. Please confirm its orientation before soldering to avoid discovering after soldering that pressing down is for power off and lifting up is for power on.
2. It is recommended to ground the circuit and also use an anti-static wrist strap to ground your body during use.