Difference between revisions of "DESK-MX6-L/Peripherals/GPIOs"

From DAVE Developer's Wiki
Jump to: navigation, search
m (U0007 moved page DESK-MX6-L/Pheripherals/GPIOs to DESK-MX6-L/Peripherals/GPIOs without leaving a redirect)
(7 intermediate revisions by 2 users not shown)
Line 3: Line 3:
 
! colspan="4" style="width:100%; text-align:left" ; border-bottom:solid 2px #ededed" |History
 
! colspan="4" style="width:100%; text-align:left" ; border-bottom:solid 2px #ededed" |History
 
|-  
 
|-  
 +
! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white" |Version
 
! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white" |Issue Date
 
! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white" |Issue Date
 
! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white" |Notes
 
! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white" |Notes
 
|-
 
|-
−
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |{{oldid|14083|2021/07/16}}
+
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |{{oldid|14083|1.0.0}}
−
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |First DESK-MX6-L release
+
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |Oct 2020
−
|-
+
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |First DESK release
−
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |{{oldid|17005|2022/03/03}}
 
−
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |DESK-MX6-L 3.0.0 release
 
−
|-
 
−
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |{{oldid|17064|2022/10/04}}
 
−
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |Add libgpiod example
 
−
|-
 
−
 
 
−
! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#ededed; padding:5px; color:#000000" |2023/04/11
 
−
! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#ededed; padding:5px; color:#000000" |DESK-MX6-L 4.0.0 release
 
 
|-
 
|-
 +
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |2.0.0
 +
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |Feb 2022
 +
| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |DESK 3.0.0 release
 
|}
 
|}
 
<section end="History" />
 
<section end="History" />
Line 73: Line 68:
 
root@desk-mx6:~# ls -la /sys/class/leds/
 
root@desk-mx6:~# ls -la /sys/class/leds/
 
total 0
 
total 0
−
drwxr-xr-x  2 root root 0 Apr 28 2022 .
+
drwxr-xr-x  2 root root 0 Apr  2  2020 .
−
drwxr-xr-x 58 root root 0 Apr 28 2022 ..
+
drwxr-xr-x 54 root root 0 Apr  2  2020 ..
−
lrwxrwxrwx  1 root root 0 Apr 28 2022 mmc0:: -> ../../devices/platform/soc/2100000.bus/2190000.mmc/leds/mmc0::
+
lrwxrwxrwx  1 root root 0 Apr  2  2020 mmc0:: -> ../../devices/soc0/soc/2100000.aips-bus/2190000.usdhc/leds/mmc0::
−
lrwxrwxrwx  1 root root 0 Apr 28 2022 mmc1:: -> ../../devices/platform/soc/2100000.bus/2194000.mmc/leds/mmc1::
+
lrwxrwxrwx  1 root root 0 Apr  2  2020 mmc1:: -> ../../devices/soc0/soc/2100000.aips-bus/2194000.usdhc/leds/mmc1::
−
lrwxrwxrwx  1 root root 0 Apr 28 2022 rs232_485_422 -> ../../devices/platform/leds/leds/rs232_485_422
+
lrwxrwxrwx  1 root root 0 Apr  2  2020 rs232_485_422 -> ../../devices/soc0/leds/leds/rs232_485_422
−
lrwxrwxrwx  1 root root 0 Apr 28 2022 rs232_on -> ../../devices/platform/leds/leds/rs232_on
+
lrwxrwxrwx  1 root root 0 Apr  2  2020 rs232_on -> ../../devices/soc0/leds/leds/rs232_on
 +
root@desk-mx6:~#
 
</pre>
 
</pre>
  
−
===Userspace gpio access ===
 
 
==== Usage with [https://www.kernel.org/doc/Documentation/gpio/sysfs.txt sysfs] ====
 
==== Usage with [https://www.kernel.org/doc/Documentation/gpio/sysfs.txt sysfs] ====
  
Line 104: Line 99:
 
</pre>
 
</pre>
  
−
===== Additional information =====
+
=== Additional information ===
−
Information about GPIOs usage under <code>sysfs</code> directory ''https://www.kernel.org/doc/Documentation/gpio/sysfs.txt''
+
Information about GPIOs usage under sysfs directory ''https://www.kernel.org/doc/Documentation/gpio/sysfs.txt''
  
−
==== Usage with [https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/tree/README libgpiod] ====
+
{{WarningMessage|text=''sysfs'' GPIO ABI has been deprecated. See more inofrmation [https://www.kernel.org/doc/Documentation/gpio/sysfs.rst here] about it. A character device access has to be used, more information [https://embeddedbits.org/new-linux-kernel-gpio-user-space-interface/ here]}}
−
 
 
−
{{WarningMessage|text=''sysfs'' GPIO ABI has been deprecated. See more information [https://www.kernel.org/doc/Documentation/gpio/sysfs.rst here] about it. A character device access has to be used, more information [https://embeddedbits.org/new-linux-kernel-gpio-user-space-interface/ here]}}
 
  
 
Information about GPIOs library '''libgpiod''' - C library and tools - can be found on [https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/ git.kernel.org]  
 
Information about GPIOs library '''libgpiod''' - C library and tools - can be found on [https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/ git.kernel.org]  
−
 
−
===== libgpiod example =====
 
−
It is possible yo cross-compile <code>libgpiod</code> in the target (if the related Yocto package is not available for installation). Once the ''autoconf-archive'' package has been installed
 
−
<pre>
 
−
dnf install autoconf-archive
 
−
</pre>
 
−
 
−
it is possible to clone the <code>libgpiod</code> git repository and compile the related sources:
 
−
 
−
<pre>
 
−
git clone https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git
 
−
cd libgpiod
 
−
./autogen.sh --enable-tools=yes --prefix=/usr/local
 
−
make
 
−
make install
 
−
</pre>
 
−
 
−
Once installed, the <code>gpio</code> utilities are availabel in the target:
 
−
 
−
<pre class="workstation-terminal">
 
−
root@desk-mx6:~# gpio
 
−
gpiodetect  gpiofind    gpioget    gpioinfo    gpiomon    gpioset
 
−
</pre>
 
−
 
−
===== gpio interrupt example =====
 
−
If a push button, with proper pull-up, is connected to a GPIO line available - for example using the J33.34 pin available on [[AXEL_Lite_SOM/AXEL_Lite_Evaluation_Kit/Interfaces_and_Connectors/WIDE | SBC AXEL Lite WIDE]] connector - the related GPIO can be used as an interrupt:
 
−
 
−
* J33.40 is connected to J10.40 SOM pin
 
−
** J33 connector is the WIDE connector in the [[AXEL_Lite_SOM/AXEL_Lite_Evaluation_Kit | AXEL Lite EVK]]
 
−
** J10 connector is the SO-DIMM connector in the AXEL Lite EVK
 
−
** ALT-5 alternate function for this pin is <code>GPIO1_IO06</code>
 
−
* the corresponding pin number is 0 6
 
−
* <code>gpiomon</code> utility can be used for monitor the pin status and triggering, for example, the ''falling-edge'' event:
 
−
 
−
<pre class="workstation-terminal">
 
−
root@desk-mx6:~# gpiomon --falling-edge 0 6
 
−
event: FALLING EDGE offset: 6 timestamp: [    696.463539802]
 
−
event: FALLING EDGE offset: 6 timestamp: [    696.643661944]
 
−
^Croot@desk-mx6:~#
 
−
</pre>
 
  
 
<section end="Body" />
 
<section end="Body" />

Revision as of 15:29, 3 March 2022

HOME SOMs SBCs ToloMEO Embedded Assistant Sale-tag.pngGET A QUOTE Customer-service.pngONLINE HELPDESK
Roadmap IoT Services ML/AI services Embedded Design Services
History
Version Issue Date Notes

1.0.0

Oct 2020 First DESK release
2.0.0 Feb 2022 DESK 3.0.0 release


Peripheral GPIOs[edit | edit source]

i.MX6 can handle external pins in many different ways and most of them can be configured as GPIOs. When a pin is set as a GPIO, it is possible to read its value, change its direction or change output value directly from the shell.

Device tree configuration[edit | edit source]

Here below an example of device tree configuration for using the RS-485 GPIOs used on standard DAVE's kit for the AXEL Lite SOM:

From imx6q-sbcx-cb0012.dts: 

    leds {
        compatible = "gpio-leds";
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_rs232_485_422_1>;

        rs232_485_422 {
            gpios = <&gpio7 13 GPIO_ACTIVE_HIGH>;
            linux,default-trigger = "default-on";
        };

        rs232_on {
            gpios = <&gpio5 29 GPIO_ACTIVE_LOW>;
            linux,default-trigger = "default-on";
        };
    };
};

From mx6qdl-sbcx-revb-common.dtsi: 

    rs232_485_422 {
        pinctrl_rs232_485_422_1: pinctrl_rs232_485_422_grp-1 {
            fsl,pins = <
                MX6QDL_PAD_GPIO_18__GPIO7_IO13      0x1b0b1 /* UART5_485/232 */
                MX6QDL_PAD_CSI0_DAT11__GPIO5_IO29   0x1b0b1 /* UART5_ON */
            >;
        };
    };

Accessing the peripheral[edit | edit source]

Linux messages at boot time[edit | edit source]

With the previous leds configuration for the GPIOs, it is possible to find them on sysfs under /sys/class/leds sub-directory: 

root@desk-mx6:~# ls -la /sys/class/leds/
total 0
drwxr-xr-x  2 root root 0 Apr  2  2020 .
drwxr-xr-x 54 root root 0 Apr  2  2020 ..
lrwxrwxrwx  1 root root 0 Apr  2  2020 mmc0:: -> ../../devices/soc0/soc/2100000.aips-bus/2190000.usdhc/leds/mmc0::
lrwxrwxrwx  1 root root 0 Apr  2  2020 mmc1:: -> ../../devices/soc0/soc/2100000.aips-bus/2194000.usdhc/leds/mmc1::
lrwxrwxrwx  1 root root 0 Apr  2  2020 rs232_485_422 -> ../../devices/soc0/leds/leds/rs232_485_422
lrwxrwxrwx  1 root root 0 Apr  2  2020 rs232_on -> ../../devices/soc0/leds/leds/rs232_on
root@desk-mx6:~#

Usage with sysfs[edit | edit source]

  • set EIM_D26 (MX6QDL_PAD_EIM_D26__GPIO3_IO26) as output GPIO
    • GPIO3_IO26 => (n-1)*32 + IO = (3-1)*32+26 = 90
root@desk-mx6:~# echo 90 > /sys/class/gpio/export
root@desk-mx6:~# echo out > /sys/class/gpio/gpio90/direction
root@desk-mx6:~# echo 1 > /sys/class/gpio/gpio90/value
root@desk-mx6:~#
  • set EIM_D27 (MX6QDL_PAD_EIM_D27__GPIO3_IO27) as input GPIO
root@desk-mx6:~# echo 91 > /sys/class/gpio/export
root@desk-mx6:~# echo in > /sys/class/gpio/gpio91/direction
root@desk-mx6:~# cat /sys/class/gpio/gpio91/value
1
root@desk-mx6:~#

Additional information[edit | edit source]

Information about GPIOs usage under sysfs directory https://www.kernel.org/doc/Documentation/gpio/sysfs.txt


Warning-icon.png sysfs GPIO ABI has been deprecated. See more inofrmation here about it. A character device access has to be used, more information here Warning-icon.png

Information about GPIOs library libgpiod - C library and tools - can be found on git.kernel.org


HOME SOMs SBCs ToloMEO Embedded Assistant Sale-tag.pngGET A QUOTE Customer-service.pngONLINE HELPDESK
Roadmap IoT Services ML/AI services Embedded Design Services
Retrieved from "https://wiki.dave.eu/index.php?title=DESK-MX6-L/Peripherals/GPIOs&oldid=16267"