I tried your suggestion but it didn't work :( In the video as well, Derek had to change the pin direction to "out" manually.
I think I am simply missing the big point of what device overlay does... @Dacobi: Can you please clarify your comment regarding "default mode of the pin (for instance pull-op/down resistors) " Is Direction of pin independent of what you menationed? root@beaglebone:/sys/class/gpio/gpio30# cat $SLOTS 0: 54:PF--- 1: 55:PF--- 2: 56:PF--- 3: 57:PF--- 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G 5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI 6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN 8: ff:P-O-L Override Board Name,00A0,Override Manuf,MY-LED root@beaglebone:/sys/class/gpio/gpio30# cat direction in root@beaglebone:/sys/class/gpio/gpio30# @Mickae1: Also my kernel is 3.18 root@beaglebone:/sys/class/gpio/gpio30# uname -r 3.8.13-bone47 On Tuesday, 9 December 2014 12:42:38 UTC, Mickae1 wrote: > > One of the main reason of the device overlay is to stop having different > kernel for different plateform ! In the device overlay you specify your > hardware at boot. Most of the time you don't change your connection after > the boot ! > > In the kernel 3.14, there is no capemanager, so you need to recompile the > dts file to specify which cape you want. ( include device tree file of the > cap ) . > > That it ! > > Le Tue Dec 09 2014 at 08:21:22, Hemant Kapoor <[email protected] > <javascript:>> a écrit : > >> Thanks Jan and Dacobi for your valuable comments. >> >> There is one small confusion. I declared the pin to be an output pin in >> my device tree overlay: >> >> 0x870 0x07 /* output mode | MODE7, see Pin_Configuration.pdf in >> BBB */ >> >> but after exporting pin as you guys mentioned and looking at the >> direction, I get it as 'in' >> >> root@beaglebone:/sys/class/gpio/gpio60# cat direction >> in >> >> The below steps described by Jan could be done without the use of device >> overlay >> >> >> >> >> cd /sys/class/gpio >> cd gpio60 >> echo 60 > export >> echo out > direction >> >> >> echo 1 > value >> >> So why do we need device overlay :( >> >> Please help me get rid of this confusion. It is driving me mad.... >> >> HK! >> >> >> >> >> >> On Tuesday, 9 December 2014 01:42:08 UTC, Dacobi wrote: >> >>> You need to do >>> >>> echo 60 > export >>> >>> Before >>> >>> cd gpio60 >>> >> On Dec 9, 2014 2:32 AM, <[email protected]> wrote: >>> >> A good tutorial here: >>>> http://derekmolloy.ie/gpios-on-the-beaglebone-black-using- >>>> device-tree-overlays/ >>>> simple example: >>>> cd /sys/class/gpio >>>> cd gpio60 >>>> echo 60 > export >>>> echo out > direction >>>> echo 1 > value >>>> >>>> good luck >>>> Jan >>>> >>>> >>>> >>>> >>>> >>>> >>>> On Tuesday, December 9, 2014 1:41:10 AM UTC+11, Hemant Kapoor wrote: >>>>> >>>>> Hello All, >>>>> >>>>> I am a newbie to Linux and trying to figure out how device tree >>>>> overlay works... >>>>> >>>>> So after googling for many days, I came up with below device tree: >>>>> >>>>> /dts-v1/; >>>>> /plugin/; >>>>> >>>>> / { >>>>> compatible = "ti,beaglebone", "ti,beaglebone-black"; >>>>> >>>>> /* identification */ >>>>> part-number = "MY-LED"; >>>>> version = "00A0"; >>>>> >>>>> /* state the resources this cape uses */ >>>>> exclusive-use = >>>>> /* the pin header uses */ >>>>> "P9.12", /* GPIO*/ >>>>> /* the hardware ip uses */ >>>>> "gpio0"; >>>>> >>>>> fragment@0 { >>>>> target = <&am33xx_pinmux>; >>>>> __overlay__ { >>>>> bb_mygpio_pins: pinmux_bb_mygpio_pins { >>>>> pinctrl-single,pins = < >>>>> 0x870 0x07 /* >>>>> output mode | MODE7, see Pin_Configuration.pdf in BBB */ >>>>> >; >>>>> }; >>>>> }; >>>>> }; >>>>> >>>>> fragment@1 { >>>>> target = <&ocp>; /* not sure why it is not >>>>> gpio0 */ >>>>> __overlay__ { >>>>> status = "okay"; >>>>> pinctrl-names = "default"; >>>>> pinctrl-0 = <&bb_mygpio_pins>; >>>>> }; >>>>> }; >>>>> }; >>>>> >>>>> >>>>> I was able to "build" the dtc and generated MY-LED-00A0.dtbo >>>>> >>>>> I then copied the MY-LED-00A0.dtbo to /lib/firmware >>>>> >>>>> Then i echoed it to slots: >>>>> echo MY-LED > $SLOTS >>>>> >>>>> and cat $SLOTS gives me below result: >>>>> >>>>> root@beaglebone:/lib/firmware# cat $SLOTS >>>>> 0: 54:PF--- >>>>> 1: 55:PF--- >>>>> 2: 56:PF--- >>>>> 3: 57:PF--- >>>>> 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G >>>>> 5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI >>>>> 6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN >>>>> 9: ff:P-O-L Override Board Name,00A0,Override Manuf,MY-LED >>>>> >>>>> By looks of this, MY_LED seems to be loaded... >>>>> >>>>> >>>>> The main confusion is how can I use MY-LED? >>>>> Where are the files for MY-LED present? >>>>> >>>>> Any help or guidance is much appreciated. >>>>> >>>>> -- >>>> 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 [email protected]. >>> >>> >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> -- >> 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 [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
