问题
I have run into some problem controlling usb1' power. as I investigated from "https://e2e.ti.com/support/arm/sitara_arm/f/791/t/270060" It tells me that GPIO3_13 controls usb1_drvvbus pin, which controls the usb power.
I understand that there is software method to change the voltage of this pin. My question is that where is GPIO3_13 located on P8 or P9 expansion bays? I cannot find it on any diagrams. Is it purposefully not exposed anywhere?
回答1:
You can control USB1 power from software on the beaglebone, if you are using a recent elinux.org Debian image (the necessary device tree overlay was merged in June 2015). This uses a hack to expose the usb1_drvvbus signal as a fake LED, which can then be controlled using the files in /sys.
Firstly, load the dev-USB-PWR-CTL-00A1.dtbo device tree overlay. For recent setups (where all dtbos are loaded by uboot and then passed to the kernel at boot time), this could be done by adding dtb_overlay=/lib/firmware/dev-USB-PWR-CTL-00A1.dtbo to /boot/uEnv.txt and rebooting (older kernels/uboots will need to use the older config mechanisms as described in /boot/uEnv.txt).
You can then do this:
echo 'usb1' > /sys/bus/usb/drivers/usb/unbind
echo 0 > /sys/devices/platform/leds/leds/usb_hub_power/brightness
sleep 1
echo 255 > /sys/devices/platform/leds/leds/usb_hub_power/brightness
echo 'usb1' > /sys/bus/usb/drivers/usb/bind
来源：https://stackoverflow.com/questions/45783004/beaglebone-gpio3-13-aka-gpio109-not-exposed-on-p8-or-p9