Built a cheap DIY fan controller because my motherboard never had working PWM
himthe.dev
himthe.dev
is not true. There is a diagram available for this mobo and U32 (F71889AD) is connected over LPC (modern serial ISA version). Its a full Super IO and it cant be _not connected_ as it also provides keyboard/mouse, serial and printer ports.
The problem must lie elsewhere, most likely bad BIOS.
>Here's what I knew:
> Windows can read CPU temperature directly from the CPU's internal thermal diode, completely bypassing the useless Super IO chip.
why not read temperature directly from Fintek using HwInfo?
https://www.hwinfo.com/forum/threads/faulty-sensor-readings-... and yes it also works on 970 https://forum-en.msi.com/index.php?threads/msi-970-cpu-temps...
not to mention MSI Command Center can read those sensors AND set FAN speeds/curves, and most likely also SpeedFan.
> asked LLMs
LLM failed this person :(
And I've tried a couple of versions available there. I was even able to find some beta/unreleased bioses that I've also tested. Unfortunately, none of them enable fan control or fix temp & fan speed monitoring.
Also not sure how you found that model number, it's literally an F71878AD, here's proof: https://www.modders-inc.com/wp-content/uploads/image/2015/02... Taken from here: https://www.modders-inc.com/msi-970-gaming-mobo/2/
I can show you a HWiNFO screenshot of it not reading anything off the SuperIO except Chassis Intrusion: https://imgur.com/a/dYPETWz
The only way I can get a temperature reading is off the CPU probe directly, which I am already making use of. As the article covers in later parts, I'm using HWiNFO and/or PawnIO to do exactly what you say (reading off the CPU probe sensor) and feed it into a fan curve, which then sends the appropriate duty cycle to the arduino.
In the BIOS there's no temperature reading, no fan speed display, and no PWM control whatsoever.
So maybe MSI did wire up the SuperIO, I can't say for sure, but they definitely didn't wire up something, otherwise the BIOS could at least control the fans or see their RPM.
And I've also tried with multiple BIOS versions, so it can't be BIOS related.
Some people online had working sensors on their MSI 970 boards, some didn't, leading me to believe it must've been a defective batch where they forgot something.
Image of an MSI 970 Gaming bios where temp and fans work properly: https://forum-en.msi.com/index.php?attachments/msi_snapshot_...
I assumed LLM gave you or validate the idea one of the biggest mobo manufacturers on the planet didnt wire temp/fan control on their flagship Gaming board?
>not sure how you found that model number
manufacturer diagram of MSI MS-7693 rev 2.0 (970 Gaming) https://www.elvikom.pl/viewtopic.php?lang=en&t=54275&p=21060...
> it's literally an F71878AD
rev 2 specifies F71889AD but Im pretty sure all Fintek F71868/869/870/878/882/889 are more or less compatible https://docs.kernel.org/hwmon/f71882fg.html https://www.linuxquestions.org/questions/linux-hardware-18/f...
rev 4.0 and up do list F71878AD https://www.scribd.com/document/961738196/MS-7693-Rev4-2 https://html.scribdassets.com/5xds0sz8hsgb4iux/images/27-e6d... diagram has all the fans and temp stuff wired up.
Only one pin comes to mind that would break all temp sensors, fans and Voltage monitoring but not ps2/serial/lpt, that pin is 88 analog ground.
>HWiNFO screenshot of it not reading anything
HWiNFO has this "feature" that makes it hide sensors reporting maximum/minimum possible values. HWiNFO considers such readings sign of a missing/broken sensor. Broken analog ground pin on your motherboard would make all those sensors return bad value.
Video of someone running hwinfo successfully on 970 gaming rev 4.x (F71878AD) https://www.youtube.com/watch?v=Wq50OuGC1ys
Even if I do get it fully fixed, I think my project could be useful for motherboards that have thermal probes but no PWM.
Real talk though, I'd love to see this MSI board fully operational.
I think you could check if the pin is reliably connected to ground.
Did you buy this board already broken? Its also possible someone connecting Fans shorted 12V to Fintek FAN tacho input (two middle pins on 4 pin connector) frying all ADC inputs, in that case only replacement chip would work.
Honestly I have no idea what this board has been through before getting to me. It had the PWM/Temp/RPM issue from the moment I got it. Maybe someone did break the chip. I'm gonna look up that diagram and try to see if the pin is connected to ground
Maybe the ps/2 port and serial/parallel ports also don't work? Lots of people use USB for human inputs, and few people use serial/parallel ports, so I wouldn't expect OP to have tested those ports.
They probably work on most boards, just like the PWM probably works on most boards. But his board seems to have a broken trace or a faulty chip.
Or loopback on the serial port; just have to enable it in BIOS, don't need a connector or a serial device.
An Arduino Nano generates the 25kHz PWM signal, and a companion Windows application reads CPU temp and sends the duty cycle over serial. The Arduino firmware is open source (MIT).
We don't live in the AMD Athlon era[0] anymore. Modern CPUs are designed to boost until they hit a thermal limit, improper cooling is just going to result in a lower clock speed.
But a small circuit with a Schmitt-trigger inverter IC and some resistors and capacitors might do the trick, for example.
I went through this years ago making a fan driver for my vehicles HVAC blower. The analog setup was fun to make but you use more board space, higher BOM count, and really, higher BOM cost vs a micro-controller.
However the bane of analog circuits was that they age, so a control circuit that works perfectly today will drift and no longer work as intended after some years.
The second problem is that analog circuits need adjustments to set them at the exact desired parameters.
Adjustments can be done either by using an adjustable element in the circuit, e.g. an adjustable resistor or capacitor or inductor, or by measuring many resistors and/or capacitors and/or inductors and selecting the ones with the right values to be used by your device.
Redoing periodically the adjustments also solves the aging problem. However, both the initial adjustment and any periodic readjustments need a lot of work, so they are no longer acceptable in the industry.
When doing something for yourself, you may make an analog controller and the initial adjustment would not be a problem, but even in this case it would be annoying to keep track and remember something like having to readjust a fan controller every 6 months, to be sure that it still works as intended.
Oh, you need a quadratic fan curve instead of a linear one? Have fun starting from scratch!
My point was that, if you want additional behavior, you need to bake that in from the start. With an MCU you can trivially switch it in-the-field to literally anything you can imagine.
I worked at a shop that had an old closed loop water-air chiller for a laser. The water temperature controller was a small PCB with an op-amp chip with some passives and the temperature was set by a potentiometer. That thing ran fine until the compressor died and it sent to scrap.
It's not just a dumb fan controller that I could've bought off aliexpress.
Using Arduino and serial is a smart way to go here. Still, it’s worth remembering: the Pico W has built-in WiFi, so you don’t have to lean on serial if you don’t want to. You could have your temp-reading app send control signals over HTTP instead. No need to tie up the USB port, and the connection isn’t killed if someone yanks the cable.
And yes, big agreement on the watchdog or failsafe. Any fan controller that doesn’t ramp up to 100% if it loses connection is just waiting for trouble. Fire risk is real.
We work in very hot greenhouses, so fans (and peltiers) are essential. And proper thermal sensors. I check 4 different ones. Esp. needed is also a humidity sensor, because we don't want it to cool down below the dew point.
It's PWM, controlled via mraa. mraa_pwm_write()
Peltiers have a lifetime measured in cycles, cycling from active (maximum delta Temp) to inactive (both sides ambient). After 1-2k cycles, Peltiers gradually lose efficiency and transition from a heat pump to a hot plate. For this reason I've avoided them in my own permanent installations. Have you encountered this?
First time I've come across this technology. A solid-state heat pump? Magic!
Would you mind sharing more technical review of what you created?
From my experience: ESP32/RP2040 work without additional circuitry which works with most fans, but for protection, you want to add level shifters. Not all fans pull up the PWM pin to 3.3V, the spec allows for 5V.
Shameless plug, hopefully this is allowed here.
I built something like that, that allows fan control via WiFi. First I built it only for myself, but since the spare boards from PCBA quickly sold, I decided to keep it stocked.
Short gist: 12V Input, ESP32S2, ESPHome-based. Has 4 PWM-fan outputs, onboard temperature & humidity sensor and Qwiic expansion port.
The ESPHome code & schematic is on Github: https://github.com/zeroflow/wifi-fancontroller
If you want one, it's available on Elecrow for $35,99: https://www.elecrow.com/wifi-fancontroller1.html
If you want to build it by yourself, the schematic is in the hardware folder. And if you don't want to use ESPHome - there is no firmware lock, you find the pin assignment on the product page and can write your own firmware if you so desire.