[PD protocol | High appearance] mini heating table

 
The protocol chip uses IP2721 to trick out a 20V voltage.
The display uses a 0.91-inch OLED module.
The main control chip is STC8H3K32S.
Because the heating platform is too small, the screen almost occupies the entire front of the fuselage, so the buttons can only be set on the back of the fuselage.
1. The software
default page displays the real-time temperature in the upper left corner, the voltage and set temperature in the middle, the heating status (constant temperature, heating, off) in the upper right corner,
the actual temperature and set temperature in the lower left corner, and the PWM duty cycle (real-time power) in the lower right corner.
Short press or long press the left and right buttons to increase or decrease the set temperature. Short press the two buttons at the same time to turn the output on and off. Press and hold the two buttons
at the same time to enter the setting page.
On the setting page, short press the left and right buttons to adjust the options. Short
press the two buttons at the same time to confirm.
Long press the two buttons at the same time to return.
Short press the two buttons at the same time on the return option to return.
PID parameter setting interface↑
The options that can be set include three parameters of PID,
temperature setting interface↑
The maximum and minimum temperature limits,
and the display mode can be changed at the same time. The display modes include detailed information display mode and temperature curve mode. The detailed information interface will display temperature, power supply voltage, heating status, power and other information (the picture at the beginning of the article is the detailed information display mode)
Real-time temperature curve display interface
When changed to real-time temperature curve mode, most of the information on the main page is omitted, only the actual temperature, set temperature and heating switch are retained, but the real-time temperature curve will be displayed, updated every 1 second, and can record about 100 seconds of temperature information. The dotted line is the set temperature.
 
The settings will be recorded in the eeprom and will not be lost when the power is off.
Change the IRC frequency to 35MHz before burning the program, and click "Download/Program".
Note: Some official STC and Zhongjingyuan library functions are used in the program.
2. Hardware
M3*12mm double-pass studs*4; //Cannot be too long or too short
M3*5+6mm single-pass studs*4; //Not recommended to be too short or too long, can be slightly longer
M3*5 double-pass studs*8; //Not recommended to be too short or too long, can be slightly longer
M3*3 flat head screws*28; //Screw length <= (short double-pass stud length + 2*1.6)
M3*8 flat head screws*4; //Cannot be shorter, can be slightly longer, 8<=length<=10
M3*3 copper flower nuts/inlaid nuts*12;
P100 test pin * 2; //Use the test pin to connect the mainboard and the heating plate. It is recommended to use a round head with a length of about 33mm
PT1000 platinum resistor; //Used for temperature measurement
Copper flower nut/inlaid nut↑
Main control board↑
Close-up of the relative position of the test pin hole and the screen↑Close
-up of the test pin after installing the aluminum substrate↑
Use thermal conductive glue to stick the thermistor under the aluminum substrate (aluminum side facing up). The resistance of the aluminum substrate is about 6 ohms. When powered by 20V, the power is about 65w. If you want to increase the power, please increase the width of the aluminum substrate wiring.
The screen connector and the thermistor connector on the main control board can choose to weld the socket or directly weld the wire. Pay attention to the line sequence of the screen interface. Thermistor has no polarity.
Install the button into the shell.
Screw the long screws and copper flower nuts on the bottom plate and place them on the bottom of the shell (pay attention to the direction), then install the mainboard into the shell from the side of the button and use the copper flower nut to fix it to the bottom plate.
Install the 12mm stud into the shell, tighten the bottom plate screws, and connect the screen and thermistor to the mainboard.
Install the top plate, use 5+6 single-pass studs to fix the top plate to the outer shell, and then install the heat insulation board in turn. (Note the direction of the reserved test pin hole)
Insert the test pin (the test pin does not need to be welded), weld the thermistor connecting wire, and tighten the screws to fix the aluminum substrate.
Done! (The Taobao details page of the test pin shows that the maximum current it can withstand is 3A, which is enough.)
 
There is a screen panel in the open source design drawing, which is printed using the Jialichuang panel and can be used as a protective panel for the screen. Order link: https://dos.szlcsc.com/
 
The bom is based on the PCB, and the automatically generated bom may be incorrect.
 
September 26: The display bug of the progress bar has been fixed, and the button bug has been fixed.
 
B station video: Let's make a small and beautiful heating table_哔哩哔哩_bilibili