Compute Module 4 IO Board Fan

[andrea9nta]

Hi all!
I want to regulate the speed of a fan connected to the fan header of my compute module 4 io board. From the datasheet I've read that it's connected to a EMC2301 chip but I cannot figure out how to control it. I am using the raspbian lite OS with rebuilt kernel (64bit and sata support).

Thanks in advance to all

[aBUGSworstnightmare]

It's controlled via PWM. The EMC2301 (https://www.microchip.com/wwwproducts/en/EMC2301 ) sits on the I2C bus .
It has two addresses: 0x0c is the alert response address of SMBBus (0001_100xb); device address is 0x2f (0101_111(r/w)b)

With 'dtparam=i2c_vc=on' added to config.txt I get below from the CM4IO

Code: Select all

pi@raspberrypi:~ $ sudo i2cdetect -y 10
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- 0c -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2f 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- 51 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --     

the data sheet has the details on the device. Sorry, but don't know if there is a kernel driver for the PWM controller.

[Icarus_Radio]

It's controlled via PWM. The EMC2301 (https://www.microchip.com/wwwproducts/en/EMC2301 ) sits on the I2C bus .
It has two addresses: 0x0c is the alert response address of SMBBus (0001_100xb); device address is 0x2f (0101_111(r/w)b)

With 'dtparam=i2c_vc=on' added to config.txt I get below from the CM4IO

Code: Select all

pi@raspberrypi:~ $ sudo i2cdetect -y 10
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- 0c -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2f 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- 51 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --     

the data sheet has the details on the device. Sorry, but don't know if there is a kernel driver for the PWM controller.

It seems that Linux has a PWM interface (https://www.kernel.org/doc/html/latest/ ... i/pwm.html). I am wondering how to control the fan as well. Any help is appreciated.

[aBUGSworstnightmare]

It's controlled via PWM. The EMC2301 (https://www.microchip.com/wwwproducts/en/EMC2301 ) sits on the I2C bus .
It has two addresses: 0x0c is the alert response address of SMBBus (0001_100xb); device address is 0x2f (0101_111(r/w)b)

With 'dtparam=i2c_vc=on' added to config.txt I get below from the CM4IO

Code: Select all

pi@raspberrypi:~ $ sudo i2cdetect -y 10
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- 0c -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2f 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- 51 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --     

the data sheet has the details on the device. Sorry, but don't know if there is a kernel driver for the PWM controller.

It seems that Linux has a PWM interface (https://www.kernel.org/doc/html/latest/ ... i/pwm.html). I am wondering how to control the fan as well. Any help is appreciated.

if you simply want to have it temperature controled simply enable that feature. 'Controlling' it has a different understanding to me.

[andrea9nta]

By 'Controlling' I mean adjust automatically the speed of the fan in relation of temperature. If this is not possible it would be fine to only adjust it to a speed lower than 100%.

[LakshmiN]

https://github.com/opennetworklinux/lin ... wmon.patch

[aBUGSworstnightmare]

Temperature control is avaialble from the OS; open Raspi Config and enable it. The default GPIO setting should not be changed for the CM4IO, so you only need to set the temp level when the fan kicks in.

If you want your own profile use the kernel driver.