RTK20-Main-Board copy

# Homemade ultra-thin and compact heating table (good appearance)

# Currently V1.1 has been updated, and the prototype has been returned for verification. The updated content will be marked in the schematic and PCB. The missing shell PCB file has been added, with the beginning prefix: GHS - 2021.12.30

Software structure open source address: [https://gitee.com/liao_zhelin/rtk20-heat-bed](https://gitee.com/liao_zhelin/rtk20-heat-bed)

The inspiration of this heating table Sourced from [GeekStart Zhan Shuo](%5Bhttps://oshwhub.com/GeekStartzhan-shuo/GSH_Bed-lv-ji-ban-jia-re-ping-tai%5D(https://oshwhub.com/GeekStartzhan-shuo /GSH_Bed-lv-ji-ban-jia-re-ping-tai)) open source aluminum substrate heating table, prototyped the final 100W 20V version, and found that the size and power are very suitable for DIYers (using PD decoy and laptop power supply ), so I came up with the idea of ​​making this small heating table. The original author used arduino+LCD1206 for temperature control and 3D printing for the shell. Although it is very practical, I want to make it smaller and add reflow soldering to control the temperature. Function.
The PCB is used as the outer frame pad + conductive pillar to supply power to the uppermost aluminum substrate heating plate, and is cut and insulated. The lower PCB main control board V1.0 underestimates the thermal conductivity of the PCB. When the upper part is 230°, the main The control board has an angle of 65°. The next version is undergoing slotting and zoning copper paving, supplemented by thermal insulation cotton, and is being modified.
The circuit part uses STM32F030F4P6 as the main control. I didn't notice that the FLASH of this chip is too small, only 16K. In order to facilitate code reuse and improve development efficiency, cubemx is used to generate the underlying HAL code. The FLASH is a bit large, so the hidden 16K of F4P6 is used. The space is composed of 32KB FLASH, the u8g2 library is transplanted to drive OLED, and the STM32 hardware Superi2c is used. The speed can reach 1000 and the screen can be refreshed smoothly. PWM+DMA is used to drive the RGB lights of WS2812. After passing through the thermistor and the conditioning circuit of the op amp, the temperature is obtained by looking up the table, and PID closed-loop control is performed. Onboard input current and voltage detection, the current detection is built using LM358 low-end detection circuit. It can test the input power power and calculate the heating plate resistance (the next version may directly replace the thermistor with the heating plate resistance change), and there are also some buzzers, such as 24C02, which I will not go into detail.
![WeChat Picture_20211225143450.jpg]
When heated, the RGB will change color, and this logic will be modified to be more beautiful later
! [WeChat Picture_20211225143614.jpg]
Supports DC port and TypeC port deception power supply, through 224K chip deception, It will not be damaged even if two ports are plugged in at the same time. The insertion detection pin of the DC port is used for isolation.
The input power supply step-down part was designed with some thought and used a single-button power-off circuit, which can realize power control on the hardware and can also reuse the buttons.
The following is a photo of the first version of the prototype. There are some problems with heat insulation and circuitry that are being improved. The second version is being modified. You can wait for me to verify it before proofing. The program part is still being improved, and the peripheral drivers are basically The packaging is done, and the control part and interaction part are still being written: For
the PCB shell part, you can check out my other open source project GHS_Bed.
Other functions are being added, and the progress will be updated after improvements! [WeChat picture_20211225143458.jpg]