This PCB is used to populate the necessary electronics for my custom coil winder circuit. The circuit is built around an STM32F401-based microcontroller. The user has two buttons and a rotary encoder with a switch to navigate in the menu displayed on a Nokia 5110 LCD. The two stepper motors (feeder and main shaft) are driven by a DRV8825 stepper motor driver. The PCB also has MP2315 voltage regulator that converts the input voltage to 3.3 V which then powers the microcontroller, the display, the buttons and the rotary encoder.

This PCB and the software I provide on my website allow anyone to build their own coil winder based on two stepper motors. The already prepared PCB helps us to get rid of a serious amount of wires and the code I wrote makes it possible for anyone without any programming knowledge to automatically wind their own coils.

[2024-07-29 UPDATE]

In this update, I made some changes to the board and added more files for easier manufacturing.

I revised the PCB (as of now, v1.2) and made the following changes:

• Replaced the LDO voltage regulator with a DC-DC buck converter. This lifts the restriction of the maximum allowed input voltage of 15 V and increases it to 24 V. Also, no hot components because the DC-DC converter does not dissipate the voltage difference (input voltage - 3.3 V) as heat.
• I updated most of the text on the PCB to make it more clear and readable.
• I added a power indicator LED so the user can see if the device is getting power.
• I replaced the mounting holes (simple drill holes in the PCB) with padded holes. It looks better and it is stronger as well.
• I added a little artistic touch to the board by making the traces curved.

Regarding the voltage regulator, one has to do a little work in order to set it to 3.3 V. Right behind the potentiometer on the bottom side of the PCB, there is a tiny trace section that must be cut. Them the solder tabs at the text "3.3V" must be soldered together with a blob of solder. Please double-check the output voltage of the voltage regulator before soldering it into the PCB!!!