Do you have clear and complete requirements of what need to be programmed?
these are no requirements but just what I thought to see (going quickly through the tube)
- START STOP switch - from Arduino
- POTMETER controlled FAN
- + - buttons to control temperature
- Edit button for temperature / time
- Temperature sensor - type LM35
- I2C display to show temperature
- Countdown clock
- ...
This should take max 3 days including testing
Can you elaborate the requirements?
What type of temp sensor is used?
Do you have the schematic?
PM me if you want discuss further.
update
SCHEMATIC @13:20 in the tube
The potmeter and fan are not controlled by the Arduino (only on/off, not RPM)
which is a pity as it would allow for more control