[Macchiato] Fan control

[Stuart Monteith]

Hi,
	I’m in the process of experimenting with a microcontroller to turn the bin on and off. I was quite pleased to find that the TDM port’s I2C lines would recognise my Teensy-LC micro-controller speaking I2C. I’m currently studying the IPMI protocol as I’d like to drive and configure the microcontroller that way too. I was also thinking of hooking up the case fans to it too, but I haven’t come to any conclusion as to what to base the fan speeds.

The microcontroller, so far, would be connected to the ATX power supply (GND, +5VSB, PSON), power switch, power LED, reset switch (in parallel with case switch), USB-serial to my server,  TDM for I2C control from the system itself. I reckon with a 5V line from ATX a fan or two could be connected. The reason why I’ve been wanting to do this was so that machine could shut itself down when my UPS was off the mains.

BR,
   Stuart


Stuart Monteith
stoo at stoo.me.uk




> On 6 Apr 2018, at 23:39, Matt Sealey <neko at bakuhatsu.net> wrote:
> 
> 
> Having software toggle a GPIO fast enough to effect PWM would be highly processor intensive. that would heat the package meaning running the fan faster, you’ll make yourself a nice feedback loop!
> 
> There is a thermal diode and a way to calibrate and use it since U-Boot reports it and I can see the temp in sysfs (it reacts to the diode on my case fan speeding up the case fan and moving more air...).
> 
> I’m just not sure you could do a lot with it just being a GPIO, the only clock-like function for that pin is the MDIO clock for one of the Ethernet PHYs - if you can prove that same clock is not exported, though, you could use clock management to do what you want. MDIO clocks aren’t fast though, so it may be the difference between full off, very slow rpm (if the fan supports that range of duty cycle) and full on, not a nice temperature-controlled swing.
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.einval.com/pipermail/macchiato/attachments/20180407/534c39e0/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 874 bytes
Desc: Message signed with OpenPGP
URL: <http://lists.einval.com/pipermail/macchiato/attachments/20180407/534c39e0/attachment-0001.sig>