Fan control for oPI5 and others

[wdtz]

and, BTW, this will probably work on any SBC that has pwm and working port of wiringPi
(wiringOP is much simpler than the dtbo method, IMO)
WHY:  I don't like fans that run full speed ALL the time
pwm fans are a bit limited on the ground in small size, and expensive
The SBC has pwm pins, so why not use them
none of the examples I have  found are adequate, either gpio off/full
or excessive python scripts, 40 lines or more,, the bash script is ~ 10 lines
Some of the wiringOP/gpio packages don't work (ubuntu-full desktop)
try the commands in rc.local, if they don't work, then,,,  dpkg -l |grep wiring; apt remove .....
git clone https://github.com/orangepi-xunlong/wiringOP.git,, also install lm-sensors
(you may have to make link, this puts gpio in /usr/local/bin, this is branch next)
in rc.local:    gpio mode 0 pwm   #using wPi pin #'s, from gpio readall
                    sleep 500e-3           #pause needed
                    gpio pwm 0 900      #starts for sure
                    gpio pwm 0 380      #slow to MIN until cron adjusts
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gpio pwm <pin> NNN ,,,, NNN is what I will call PWR, to get range give a PWR too large, the error will give range
If the PWR is too low the the fan won't start, even 800 is only 90% start
The fan turns all the time, but not at full speed, at MIN you can almost count the turns (maybe 150 rpm)
You have to find the PWR number for MIN for your fan, start at 300, it should run for hours, if not add 20, retest
When you get some #, then add 10%. With this number, fan should run forever
the script that cron calls every minute or 2
#!/usr/bin/bash
TEMP=`sensors|grep bigcore0 -A3 |grep temp1 |tr -s ' '| cut -d ' ' -f 2|cut -c 2-3`  #adjust grep as suitable, fails >99
echo $TEMP
#TEMP=$1                        #for testing, will error if $1 is blank
PWR=$(("$TEMP" * 11))          #or any other number you choose
echo $PWR
if [ "$PWR" -gt 999 ]; then     #check to see if PWR is in 'correct' range
    PWR=999
elif [ "$PWR" -lt 380 ] ; then       #if this number is suitable for YOUR fan
    PWR=380
fi
gpio pwm 0 $PWR
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obviously comment out echo lines when debugging finished
And now the wiring, it is stupid simple (arrows are both connections AND current flow)
(-ve)  <--  E
pwm  --> R --> B
(+ve)  --> Fan  --> C
if R is 1k, not enough drive to turn on transistor, 330 is 'iffy', 220 is OK, I have 180, depends on transistor
Oh, BTW, scope told me pulses are +, so transistor is NPN, if you couldn't follow circuit logic (TO92 OK, unless fan huge)
----
and now pwmTone,,, absolutely nothing on web
gpio pwmTone <pin> <frequency>  ,, sounds good, right. well range likely changes, neutral as long as you know
plus: fan starts MUCH better, even 1/2 PWR
minus: fan barely slows down even with very low PWR
If anyone knows more, please reply..... maybe there should be 5-10k pwm --> (-ve) to ensure pwm turn-off???
---- I guess if you don't have a scope you could feed a LED + R, see if it dims (? R=100?) as you change PWR

PS I would suggest this be pinned, if it is considered suitable

---------

And a better debugged script, better than off the top (of my head)

paying more attention to the hw side and not forgetting anything

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#!/usr/bin/bash
TEMP=`sensors|grep bigcore0 -A3 |grep temp1 |tr -s ' '| cut -d ' ' -f 2|cut -c 2-3`  #adjust grep as suitable, fails >9
echo $TEMP
if [ $# -gt 0 ]; then
    TEMP=$1                        #for testing
fi
PWR=$(($TEMP * 11))          #or any other number you choose
if [ "$TEMP" -lt 50 ]; then
    PWR=$(($TEMP * 8))
elif [ "$TEMP" -lt 60 ]; then
    PWR=$(($TEMP * 9))
elif [ "$TEMP" -lt 70 ]; then
    PWR=$(($TEMP * 10))
fi
echo $PWR
if [ "$PWR" -gt 999 ]; then     #check to see if PWR is in 'correct' range
    PWR=999
elif [ "$PWR" -lt 380 ]; then       #if this number is suitable for YOUR fan
    PWR=380
fi
echo $PWR
gpio pwm 0 $PWR

Edited January 18 by wdtz
syntax