The 3D printer motherboard uses the F103C8T6 core board and TMC2209 driver.

This is a motherboard I built on a whim using my old blue motherboard. I've already done a basic test of its functions, but I'm not a professional and my design skills are limited, so I can't completely guarantee that there won't be any problems or malfunctions.
It

uses KLIPPER firmware and is powered by 24V.
Five TMC2209 driver interfaces (but it was later discovered that the TMC2209 UART addressing only has 4, so only 4 2209 drivers can be connected when using UART mode, and the rest are driven by external step/dir modules),
one heating output (power is limited and should not exceed 200W for extended periods) (it is planned to use a CAN board to control the tool head, so there is only one heating output),
2 temperature measurement channels,
9 limit switch interfaces,
2 24V fan interfaces,
3 servo motor interfaces
, and communication with the host computer via the core board's USB or CAN interface (the CAN transceiver uses slope mode to reduce disconnections, baud rate 500000).

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Use kiauh to compile KLIPPER firmware settings as shown in the figure (use STLink to download firmware without a bootloader).
Select the "Communication interface" column according to your needs (the figure shows CAN communication; when selecting USB, the pins are also selected as PA11/PA12). The CAN rate must be consistent with the host computer settings. When using USB, the USB baud rate in printer.cfg remains unchanged by default.
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Select whether to power the core board from the 5VBUCK circuit on the motherboard based on the core board's power supply method.
When using CAN connection, connect the motherboard power supply jumper cap shown in the diagram. When using USB connection, disconnect the jumper and power the core board via USB.
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The CAN transceiver components are on the back; if CAN is not used, they do not need to be soldered.
If a CAN transceiver is used, the terminating resistors U11 and U12 need to be selected according to the CAN bus connection. This design uses split terminating resistors, selecting two 60Ω or 1.3kΩ resistors (similar values ​​are acceptable, such as 62Ω and 1.37kΩ), so that after the CAN bus connection is completed, the resistance between the H and L sides of the bus should be around 60Ω when measured with a multimeter. Resistor R50 is used to set the transceiver to work in slope mode, reducing speed and interference. If not needed, it can be removed and directly shorted to ground. Filter capacitors C20, U9, and U13 may need to be selected with a smaller value or removed depending on the communication speed.
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The TMC2209 driver UART address setting method
uses the TMC2209 driver module, without using infinite bit zeroing. The TMC2209 uses a single-wire UART to connect to the core board RX-PA10/TX-PA9. Note that the module's UART pin position needs to be 4. The UART address is set from 0 to 3 via jumper caps, so only 4 addresses can actually be driven and set.
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The heated bed power should not be too high. During testing, only a 220mm aluminum substrate heated bed was used to heat to 80 degrees Celsius. If a high-power heated bed is required, a high-power MOS or relay module should be connected externally
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the 24V fan, ensure the positive and negative terminals correspond to the fan plug. When using KLIPPER software for PWM speed control, the cycle should be as long as possible
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Note that the power supply positive and negative terminals should not be reversed.
Only a simple diode reverse connection protection circuit was designed. In actual testing, when connected to a switching power supply, it can ensure that the circuit is not damaged for a short time under the short-circuit protection function of the switching power supply, but it cannot guarantee that there will be absolutely no problems. ...