POe Smart Coaster

A smart coaster that keeps water warm and reminds you to drink water.
   
Winter is here, and it seems to be getting cold in Guangzhou. Sometimes I forget to drink water, or it's hard to drink cold water
. To encourage "drinking more hot water," I made a smart coaster that reminds me to drink water and has a water-keeping function.
 
Over three weekends, I turned my idea into reality,
from schematic diagram to assembly. There are still many imperfections, but consider it a temporary completion.
Detailed description:
1. The total cost of circuit construction (excluding the 3D printed casing, including shipping) is approximately 10 yuan. With the 3D printed parts (0.2 yuan per gram, 20g), the total cost is 14 yuan.
2. The main controller uses an STC15W204S. Since I happened to have one on hand, I can use a cheaper compatible model. Note the timer T2.
3. Originally, I designed it to use a dome switch to detect when the cup is put down, but since it couldn't be pressed down in actual testing, I removed the metal film on the top of the dome switch and attached a raised copper strip to press the contact point (see the picture below).
4. The button and photoresistor are not used yet. You can develop their functions yourself. Note that the middle digit of the digital tube shares a pin with button1.
5. 1. Power supply requires a rated 5V 2.3A or higher (11.5W). Operating below this value for extended periods may damage the power supply.
2. The PCB conforms to JLCPCB's free prototyping rules and can be directly prototyped for free.
3. The outer casing is connected with screws, and the other end is secured with heat-resistant tape. A rubber strip (3mm thick) supports the PCB and the bottom casing. See the following image. Print files and modeling files (FreeCAD) have been uploaded as attachments.
4. Commercial use is prohibited. Free improvement and distribution are permitted, but please include a link to this project when publishing.
5. The compiled .hex file and Keil C source code (software.zip) have been uploaded as attachments
. 6. Other
 
images to be added and taken later.