Introduction

I have a PC fan that I removed from a CPU liquid cooler, and I'm powering it with a 12V power supply to use it for air filtration.
However, when it's late at night, the fan's noise is a bit loud. But isn't this a PWM fan? I could use a development board to output a PWM signal and control the speed, but then I'd be short a development board.
While searching online, I happened to come across a few useful online resources. I realized that in this day and age, this is actually possible to DIY a PCB board for simple device controls.

• Noctua PWM specifications white paper
• KiCad tutorial video from DigiKey
• TI Power Dedigner
• OSH Park
• Mouser

Functionality

Schematic - KiCad, Ti Power Deisgner

• KiCad
  

PCB Layout - KiCad

• Front side
• Back side

PCB Fabrication - OSH Park

Order Components - Mouser

Solder

Firmware

• Programmer: STLINK-V3SET
• IDE: STM32CubeIDE
• Pin Define
  • PA7: PWM, TIM14_CH1
  • PA6: tachometer, TIM16_CH1
  • PB0: Rotary Encoder A (DI)
  • PB5: Rotary Encoder B (DI)
  • PA2: USART_TX
  • PA3: USART_RX
• Rotary Encoder Debouncing
  • Use TIM3 to periodically record last 10 pin states
    • if current state is 0, and there are at least eight 1s in the history, then change state to 1
    • if current state is 1, and there are at least eight 0s in the history, then change state to 0
• Debug USART: 115200, N, 8, 1