Mr. Baybus is a microcontroller-based fan control system. It is a completely stand-alone unit, with no computer-control whatsoever.
Control comes from momentary switches on the front panel. You have 4 switches to toggle your fans on/off, and a brightness/contrast button, which switches you into a screen to alter those settings. Another press gets you back to the fan status display.
All settings are saved in EEPROM memory on-chip. So when you shut your system down, then power back up, your fans will be running the same as they were before, and your brightness and contrast will remain unchanged as well.
The display is a CrystalFontz 16×2 Serial LCD. This unit is EXCELLENT. It supports SPI transfers which is what Mr. Baybus prefers!
The fans are switched by power MOSFETs. IRL3102’s to be exact. They are rated to handle up to around 7A for a 12V circuit like this. This is of course far beyond anything I would ever want to throw at it, but it’s nice to know you have the room to expand.
Connections to the system are made via a small 4-pin connector. This facilitates 2 fans per circuit, 4 circuits in all. The connector is the same as the CD-Audio connector on your CD-Rom’s so it’s quick and easy to remove the fans.
The brains of the system come in the form of an 18-pin microcontroller. A very basic PIC16F84a. At 4MHz this little guy is going way faster than this system needs but hey, if you got it, why not. All 912 lines of code were written in assembly over the course of a few nights.
Full source code, schematics and PCB layouts are available on GitHub, enjoy!