Hi Inigo >I have been surfing around this board and I have some ideas about how it works, but I haven't figured out it yet.
It is quite a complex topic. I too spent a quite some time trying to figure out the Device Tree and once I thought I had an understanding I wrote up my notes afterwards. Perhaps you will find the document below provides some useful background. Basically its contents are the information I wish I had when I was first trying to figure out the Device Tree. http://ofitselfso.com/BeagleNotes/AboutTheDeviceTree.pdf Cheers Nic On Friday, 29 May 2015 12:28:27 UTC+1, Iñigo Martínez wrote: > > > Hi, > > I have been reading/testing information regarding Device Tree, GPIOs since > I updated to 3.14, where bone_capemgr.* has dissapaeared, trying to > understand how everything works. I have been surfing around this board and > I have some ideas about how it works, but I haven't figured out it yet. > > I have attached a proto board and I created the device tree and loaded it > using the dtb option in uEnv.txt. I think that it's loaded correctly > because I disabled the can ports and they aren't loaded anymore. > > I have the following two paths: > > /sys/devices/44e10000.control_module > /sys/devices/44e10800.pinmux > > And these paths too: > > /sys/devices/ocp/*.gpio|.i2c etc... (* = 40300000 ... 56000000) > /sys/devices/ocp/cape-universal > /sys/devices/ocp/ocp:*.pinmux (* = P8_07 ... P9_91) > > And finally regarding GPIOs: > > /sys/class/gpio/export > /sys/class/gpio/gpiochip* (* = 0, 32, 64, 96) > /sys/class/gpio/unexport > > I can use the GPIOs after exporting them, and the behaviour is correct, so > as I said, everything looks that works fine. > > Questions: > > - Is everything correct this way ? > - How can I export gpio pins at boot so I have them available ? Is > there any option in u-boot/kernel for this ? Should I create systemd > service ? > - I have been reading about beaglebone-black-pinmux and > beaglebone-universal-io too, how they fit in this setup ? Is config-pin > related with exporting gpios on boot ? > > > Thank you, > > Best regards, > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
