Building a RGB LED and Case fan, PWM controller

Started by Ryex, March 16, 2016, 03:37:47 am

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I'm planning to build a case fan controller that can also control RGB LEDs. now I know that many similar projects/products exist but none of them do ALL of what I want.  It's a project I've been obsessing over for over a year now.

The plan is simple, take a small micro-controller and set it up to get power off a molex connector. use pwm output pins on the microcontroller or an external chip to switch NPN transistors or N chanel MOSFETs feeding 12v current to either case fans or the RGB LED strips. allow reading of temperatures as well. use a Serial COM port on the micro-controller for software control of the controller. Use EEPROM to store settings for the fans and RGB strips.

Parts I have selected:

Adafruit Metro Mini 328 uses an ATmega328
Adafruit 16-Channel 12-bit PWM/Servo Driver I2C interfaced PWM chip PCA9685
Either STP16NF06 MOSFET or KSD882YS NPN Transistor

I of cource still need to find good RGB LED strips, a thermal sensor, and all the connecting components

Circuit is simple enough, 12v is applied to the collector of the NPNs apply 5v pwm to base and the emitter becomes a 12v pwm line.
3 12v pwm lines and a ground for each RGB LED strip channel.
1 12v pwm line and a ground for the fans (this is actually a point of contention for me. most case fans are 3pin constant speed 12v, ground, and hull sensor to count rpm. 4pin fans include a 4th wire for a pwn signal. but thers not really a reson you can use pwm on the 12v line on either type fan for rpm control other than it stops the hull sensor form working properly, I think, not actualy sure. as such I'm not sure if I want to make the controller function like the motherboard standard or go for 4 pin  pwm.)

I'm having trouble deciding how many fan channels and how many RGB channels I want to make
I have 16 PWM pins to use each find need 1 each RGB strip needs 3.
I'm thinking I want 3 RGB for the top, bottom, and front of the case and than leaves plenty of fan pins but If I go with 4 RGB lines I only get 4 fan pins which seems low for my use case

I'll keep this topic updates with pictures and news.
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