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] <javascript:>> 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.
>>>
>>> --
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>
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