3S Lithium Battery Charger with LCD Display that Supports PDQC Fast Charging

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Goal:
To directly charge the lithium batteries of my 3S model aircraft using a Type-C charger.
 
Hardware solution: FUSB302 for PD protocol reading, several GPIOs + resistors + ADC for QC protocol. Main controller: STM32.
SC8802 four-switch for high current output. LCD screen: 0.77inc OLED: ZJY077-6428TSWCG02 (128x64).
 
Software solution: GUI: u8g2, that's all, purely handmade. I also ran a very lightweight scheduler.
 
Initial motivation:
After all, I'm an experienced racing drone enthusiast. So I wanted to make a 3S lithium battery charger.
Since I usually combine structure and appearance in my designs, I spent a lot of time choosing the shell.
 
My personal design goal is always to make things mass-producible (even if it has no commercial value, lol), so I prefer an integrated design.
Once something isn't mass-producible, the motivation to continue is less (I don't know why).
 
This design is a bit overdone. Personally, I feel it's not very suitable for mass production. Therefore, I've open-sourced it for everyone's reference. It's still pretty good for DIY.
 
Design Showcase:
PCBA Showcase:
The ribbon cable is used for data communication, and the header pins are used for current carrying. Due to the compact internal dimensions, the internal circuit
design
had to consider the structural dimensions when drawing the internal circuit based on the common mold casing.
This includes the ribbon cable connecting the screen and the communication ribbon cable between the boards.
 
I also added a mini fan to the design; the colored lines represent the airflow.
The left inlet draws in cold air, and the right inlet blows out hot air. Fan model: 1504.
 
Aluminum alloy casing: Keywords: Chengce casing
 
design implementation.
 
PD sink: Uses FUSB302. It can output the actual power of the charger, and the obtained power can be used to program the output current capability control of the SC8802 (essentially a multi-protocol output).
 
QC protocol: It can be tricked out using a resistor. Because it cannot output the actual current capability, it is necessary to track the maximum power point (SC8802 has this capability)
to control the current output when a significant voltage drop occurs on the line.
 
Boost/Buck: Uses the SC8802, a 4-switch solution. Frankly, 4-switch solutions are quite difficult to adjust, which is one of the reasons I think mass production feasibility is relatively low; I've always struggled with power supply adjustments.
This chip is quite capable; it can control input-side current, output-side current, and output voltage. It also has maximum power point tracking for QC.
 
Current sensing: Uses the ina226 for current monitoring.
 
Code and video documentation: Uses CubeMX, see attachment.
Also open-sourced on: Gitee.
 
Follow me on Bilibili or Douyin: 惜枫醉