Power & Source of Big Ideas

12v fan port always shows 0v across pins

Moderators: chensy, FATechsupport

How is the 12v fan output turned on? By default it seems to show 0 volts across the 12V and GND pins and the wiki only says that 12V is "controlled by GPIO4_C6/PWM1" but doesn't explain how to modulate it, or how to enable fan at all.

Also, where are we supposed to find fans with a male BM03B-GHS connector??? Why was such a completely non-standard and impossible to find connector chosen for the fan? All fans I've found online have the larger JST GH pinouts. What is the female connector's part #? Will a GHR-03V-S work if I solder it onto an existing 12v fan?

This board gets incredibly hot very quickly under load without a fan, it reaches over 90c and then just shuts down, so it would be best to offer a heatsink with a fan option and enable the fan modulation by default in the images.
While I don't know about your particular use case, you could use pin 4 and 6 from the 40 pin gpio for a simple 5V fan. However, I am also trying to figure out the male connector for the fan header, so I can't offer much more assistance than that at the moment.
Just an update on the GHR-03V-S connector, I ordered some and they finally arrived, so I can confirm that this is the appropriate connector. So you should be able to replace a fan's standard connector with this one and it should work fine. As for how to actually turn on the port for the fan, I haven't figured that out yet as I have been running android on mine recently.
Any idea how to make the fan work on android ?
ok, found it here http://wiki.friendlyarm.com/wiki/index.php/FriendlyThings_for_RK3399#PWM
in short

APIs for Accessing PWM
Export PWM0 to users
echo 0 > /sys/class/pwm/pwmchip1/export

Control a PWM fan's speed by setting the PWM's period and duty_cycle.
echo 0 > /sys/class/pwm/pwmchip1/pwm0/enable
echo 50000 > /sys/class/pwm/pwmchip1/pwm0/period
echo 1 > /sys/class/pwm/pwmchip1/pwm0/enable
echo 45000 > /sys/class/pwm/pwmchip1/pwm0/duty_cycle

period: the more you set, faster the fan will be. range is about 30k to 300k
duty_cycle: the less you set, the more speed you get. range is about 1k - 49.9k
can you please explain what to do in detail with the provided code and how to activate/execute the script?

Thanks
kirkdis wrote:
can you please explain what to do in detail with the provided code and how to activate/execute the script?

Thanks

While I don't know about your particular use case, you could use pin 4 and 6 from the 40 pin gpio for a simple 5V fan. However, I am also trying to figure out the male connector for the fan header, so I can't offer much more assistance than that at the moment.

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