Notices by Ryan Castellucci (they/them) :nonbinary_flag: (ryanc@infosec.exchange)

@stonebear2 no idea if it still works, I assume not

@jeremiah Rude!

@fullywoolly Indeed.

Still need to work up the courage to assemble the fiber optic thing, lol.

@simonzerafa I've seen those sorts of things, and they're great, but the difference here is I actually want to pretend to be a PWM fan with a tach to the motherboard. I also plan to make a single port version for e.g. control of fans in network gear where one might not be able to add software for USB control.

@CiscoJunkie There's now a standardized DHCP option to indicate the captive portal login URL, and browsers/OSs have explicit detection, so it's not as painful as it used to be.

On the other hand, the old "hook port 80 and 302" stuff doesn't work any more because ~everything is TLS.

I haven't run into a broken one for a while, tbh.

If one asks me for my email address or any other information, though, they're getting Some Bullshit.

My fan control board functions far enough to blink LEDs.

@stonebear2 https://en.wikipedia.org/wiki/Special_information_tone

@muddle also, this particular design uses low side switching for the fans - to turn them off, the ground is cut.

@muddle Each of the fans has a big MOSFET to allow it to be powered on/off, a small MOSFET to drive the PWM, a diode to protect against voltage on the tachometer, and current limiting resistors to prevent the microcontroller from trying to source too much current.

Similar circuitry is in place (except for the big MOSFET) but reversed to connect the microcontroller to the motherboard.

To the right of the microcontroller is a 3.3V linear voltage regulator (normally, a linear voltage regulator to go from 12V to 3.3V would be a bad idea, but the circuit itself only needs to draw maybe a dozen milliamps, so :thisisfine: ).

The component with a V on it is a self-resetting fuse.

@FritzAdalis Nearly all PCs have at least one I2C bus. :-)

The trick is finding a way to access it.

@FritzAdalis Nearly all PCs have at least one I2C bus. :-)

@stonebear2 https://infosec.exchange/@catsalad/116962402233245296

@FritzAdalis The motherboard interface is ground, 12V (or 5V sometimes), PWM speed control, and tachometer for monitoring RPM. My board connects to that, and then has a separate connector for I2C. On the Radxa Rock 5 ITX boards I built it for, I can hook into the I2C bus via the touch panel connector. Alternatively, I have serial broken out.

@fullywoolly It's probably just flux, but I haven't check with a multimeter.

I got one of my fan controllers (I need two) put together.

Its purpose is to connect to a motherboard PWM fan socket and then control up to three separate PWM fans, with I2C for configuration, control, and telemetry, along with serial for debugging.

Have not yet powered it on, anyone want to tell me what I messed up before I let the magic smoke out?

I also still need to write the code for it, lol.

The unpopulated resistor footprints at the top are I2C pull-ups, which I shouldn't need, but can add if I do.

@stonebear2 cat salad listed the Wikipedia article

@txo_elurmaluta @smashtie except this is a sequence of tones which that site doesn't seem to support :-(

@hypha you should

@hypha I have one, I have uses for it, yet somehow I have not used it.

Ninja Burger, but now they deliver parcels too