On Mon, 15 Apr 2024 at 19:39, Derek Atkins <derek@ihtfp.com> wrote:
>
> Hi again,
> I just went and cracked open the case.
> According the chip ID, it's an IMX6 Dual. Although cpuinfo only reports
> cpu 0.
> The main board says revision A1; the baseboard says revision A0. I guess
> this is one of my older units.
Makes sense, there was either dual or quad models, as to why it's not
finding the other core I am not sure, it might be a DT issue, might be
a kernel issue, unfortunately with F-36 EOL there's no a lot I can do
to help you there, all my imx6 devices are packed away in a box
somewhere.
> -derek
>
> On Mon, April 15, 2024 2:12 pm, Derek Atkins wrote:
> > Hi Peter,
> >
> > On Mon, April 15, 2024 1:47 pm, Peter Robinson wrote:
> >
> >>> >> I'm using
> >>> >> https://download.technexion.com/development_resources/wandboard/wbquad-revb1-userguide.pdf
> >>> >> 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.
> >>> >>
> > [snip]
> >
> >>> Being only ancillarily associated with Arm/Embedded HW -- what does it
> >>> mean for a GPIO to be "used for other things"? And more importantly,
> >>> why
> >>> would it be wired to a header if it's being used for something else?
> >>
> >> So in the case I mention below the GPIO pin is used for i2c and it's
> >> on that header so you could add say a i2c based temp sensor or other
> >> i2c device.
> >>
> >> Also board designers may use a GPIO to hook up a mSD card detect pin,
> >> or a WiFi interface reset pin, or something else on the board layout.
> >
> > I guess I don't understand why they would expose GPIO-x on a header and
> > ALSO use it elsewhere on the board. In my case, I just need to find 4
> > open "button" inputs.
> >
> >> You can see the default pin allocation here from line 152-195:
> >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/nxp/imx/imx6qdl-wandboard.dtsi#n152
> >>
> >> And the GPIOs mapped to i2c here on lines 103-104 and again 113-114,
> >> and then as a camera enable/reset at 139-140:
> >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/nxp/imx/imx6qdl-wandboard.dtsi#n103
> >
> > Thanks. I see the duplication of scl-gpois and sda-gpios names in those
> > two sections, but in the first section it uses gpio3 21/28 and in the
> > second section is used gpio4 13/14.
> >
> > I also don't see the specific bindings for the pins on the JP4 header
> > (e.g. I don't see gpio3 12 being specified here).
> >
> >>> > 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.
> >>>
> >>> How exactly is this done? Is the pin wired to two places on the PCB?
> >>
> >> It depends, for example on a RPi header you can use a DT overlay to
> >> change the default use of a PIN, by default is might be a standard
> >> GPIO but you apply an overlay that remaps it so it routes a i2s audio
> >> interface so you can use a DAC to output sound. So it's generally more
> >> about being able to use the reduced amounts of external pins for
> >> different usecases, someone might want it in a robot, someone else
> >> might want it to output audio.
> >
> > How would an end-user do that without building a custom kernel? Like I
> > said, all I need is to read from four input GPIOs for a water-detection
> > system, so instead of using a 'sleep' after opening the relay, it waits
> > for the appropriate gpio to turn on based on a water detector connected to
> > it (so it will turn off the relay as soon as it detects the water tank is
> > full).
> >
> > So really I just need to choose 4 pins that I can use, and map those to an
> > event manager to wait for the pin to go on. JP4 seems to be the only
> > layout with GPIO labeled, so I just need to figure out which pins to use
> > and how to read those inputs in this brave new world.
> >
> > Thanks,
> >
> > -derek
> >
> > --
> > Derek Atkins 617-623-3745
> > derek@ihtfp.com www.ihtfp.com
> > Computer and Internet Security Consultant
> >
> >
>
>
> --
> Derek Atkins 617-623-3745
> derek@ihtfp.com www.ihtfp.com
> Computer and Internet Security Consultant
>
--
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