unfortunate the usb power is not controlled via a gpio pin. So I don't see possibilities to cut power via that way (setting gpio pin).
Need to investigate if there are other possibilities.
ps smart idea to connect a fan to the usb port.
If you are in for some experiments
There is a gpio pin on this board for "fan power" the question where to connect the fan on this board
It maybe these three pins...(but I never tried it myself)
possible fan connector nwsp2.JPG
There are standard connectors for fans (three wires) that I think fit on that location
In the kernel setup provisions are taken to control power on/off for the fan with gpio pin 23
It can be controlled via userland like
Export the gpio pin to userland (in putty at linux prompt give this command)
- Code: Select all
echo 23 > /sys/class/gpio/export
set direction
- Code: Select all
echo out > /sys/class/gpio/gpio23/direction
power on
- Code: Select all
echo 1 > /sys/class/gpio/gpio23/value
power off
- Code: Select all
echo 0 > /sys/class/gpio/gpio23/value
If that works the feature that you want can be implemented easily, by powering up the fan at end of boot script
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