Hi Derek,
I have a Wandboard (yeah, I know, OLD Hardware) currently running a
As in the imx6 based Wandboard? Which model/rev? What release of
Fedora, what kernel etc?
project, and I'm trying to add some GPIO inputs to it. In
previous GPIO
handling (on a different platform) I used the /sys/class/gpio interfaces
to set up the GPIO, but I've discovered this is now deprecated and removed
from Fedora. So I installed libgpiod and am trying to use it.
Yes, we stopped supporting that because it was deprecated and upstream
asked us to.
I'm using
https://download.technexion.com/development_resources/wandboard/wbquad-re...
as a reference for the board layout. Specifically, on page 27, it shows
me that the JP4 header connects to GPIO3_12, GPIO3_27, GPIO6_31, CPIO1_24,
GPIO7_8, GPIO3_26, GPIO_18, and GPIO_19.
I figure that GPIO_18 is going to be gpiochip0 line 18, and GPIO3_12 will
be gpiochip3 line 12.. Except that gpiodetect only tells me I have
gpiochip0 through gpiochip6, so I'm not sure where GPIO7_8 would get
mapped. That's the first issue I have.
You'd likely need to look at the device tree and pinmappings to see
how they're mapped out.
The second issue is that the kernel does not have any named mappings,
so
running gpioinfo just displays generic data, like:
gpiochip6 - 32 lines:
line 0: unnamed unused input active-high
line 1: unnamed unused input active-high
Except, of course, looking at gpiochip3 line 12 shows me:
gpiochip3 - 32 lines:
...
line 12: unnamed "scl" output active-high [used
open-drain]
Which seems to imply that that GPIO3_12 is actually used for something
else -- or my mapping strategy is off.
Probably a kernel device, often GPIOs are used for other things.
A quick look at the dtsi for the wandboards some of the GPIOs re used
for SCL/SDA pins on two of the i2c buses. The i2c1 seems to not have
anything attached so I guess in on a pin header for end user use, and
i2c12 has a audio codec and for the camera connector.
I'd appreciate any guidance anyone might have on this subject.
If it's a iMX6 based Wandboard the guidance will be limted as the
support for ARMv7 went EOL when F-36 did so I have no recollection of
what kernel, libgpiod version etc was shipped there.
Peter