Watercooled PC Fan Monitor

I've got some PCBs made at JLCPCB.  There's a couple of minor goofs in the PCB design, but nothing too major.

• Not enough ground pins for the unused LCD pins that need to be tied to ground.
• LM317 voltage regulator gets pretty toasty.  I need to swap that out for a switchmode regulator.
• Pin header alignment is bad in a lot of cases.
• Flow rate sensor should probably be connected to TIM5 instead of TIM3.

None of these are too much of a problem and easily worked around for the time being, they can be fixed in the next revision of the PCB.

For now I'll be continuing developing the firmware.  There's still lots more to do.

Flow rate monitoring and basic RS232 comms is implemented.

Project is largely on hold at the moment.

Next step is to make a proper PCB with surface mount components, but the STM32 microcontrollers are unavailable at prototyping fab shops or anywhere really.

Liquid flow rate captured using a Koolance INS-FM14 flow rate sensor.

Basic serial console that prints out system information implemented.

Next:

Code cleanup.

Serial console input.

PWM control of fans is implemented.

Temperature monitoring is implemented

Basic control loop of reading temperature and update fan speed from curve is implemented.

Next tasks:

Implement flow rate monitoring.

Implement RS-232 serial interface.