.. _display-57:

Display
=======

The phyCORE-AM57x supports an LVDS LCD at X25, which is comprised of an LVDS signal connector and a power connector. These connectors provide connection to support various PHYTEC LCDs, such as LCD-018.  This guide will show the basic usage of an LVDS display with the phyCORE-AM57x development kit. For more information on the on the display interfaces, see section 26 in the `Hardware Manual <https://www.phytec.com/product/phycore-am57x/#section-hardware-documentation>`_.

.. image:: ../../images/phycore-am57x/pb-057948_display.png
   :width: 650px


Requirements
------------

* LCD-018-070-KAP

  * 7” LVDS Capacitive Touch Display

  * `Contact Sales <https://www.phytec.com/contact/>`_

* LCD-017-070W

  * 7" Display with Resistive Touch

  * `Contact Sales <https://www.phytec.com/contact/>`_

.. note:: Be sure that you are not using a headless BSP image as this does not support the display interface. See :ref:`ReleaseNotes-57` for more information.

Connecting the Display
-------------------------

* Verify that the DIP switches (S1) on the back of the LCD-018 are set to backlight to use the PWM setting.

  .. image:: ../../images/phycore-am57x/pb-057948_display-S1-pwm.jpg
     :width: 100px

.. note:: The backlight can be set to either: “always on”, “always off”, “PWM”, or “potentiometer”. (there is a point on the display with reference designator R30). In order to control the backlight via the phyCORE-AM57x as described in this guide, the boot switch needs to be set to PWM. (1,2,4 OFF; 3 ON).

* With the kit powered off and the power supply removed, connect the display to the connectors at X25.

  #. Open the X25 connector by gently pulling the black tab toward the edge of the board.

  #. Insert the ribbon cable into the connector, with the blue tape facing up.

  #. Once the ribbon cable has been seated into the connector, pull the black tab back towards it’s closed position.

  #. The red connector should be a standard push in connection.

  .. image:: ../../images/phycore-am57x/pb-057948_display-connection.jpg
    :width: 500px
    :alt: LCD to Carrier Board Connection


Loading the Display
-----------------------

* Power on the development kit and hit any key to stop in U-Boot.

* Load the device tree overlay needed for operating the display then boot into Linux.

.. code-block:: none
   :caption: Target (U-Boot)

   setenv overlays am57xx-phytec-pcm-948-lcd-018.dtbo
   saveenv
   boot

.. note::
   For more information about overlays see chapter :ref:`ConfiguringTheBootloader-57`.

* While the kit is booting, the PHYTEC logo with a loading bar should display on the screen. This should be followed by a "Multitouch" demo should appear.

Framebuffer Test
-------------------------

* Stop the qtdemo and weston demos.

.. code-block:: none
 :caption: Target (Linux)

 systemctl stop phytec-qtdemo
 systemctl stop weston.socket

* Run the following command to test colors and patterens.

.. code-block:: none
   :caption: Target (Linux)

   fbtest

.. code-block:: none
 :caption: Expected Output

 root@phycore-am57xx-1:~# fbtest
 Using drawops cfb32 (32 bpp packed pixels)
 Available visuals:
  Monochrome
  Grayscale 256
  Truecolor 8:8:8:0
 Using visops truecolor
 Running all tests
 test001: PASSED
 test002: PASSED
 test004: PASSED
 test006: PASSED
 test008: PASSED
 test009: PASSED

.. image:: ../../images/phycore-am57x/pb-057948_hdmi_fbtest_test001.jpg
   :width: 450px
   :alt: phyCORE-AM57x HDMI Test 1
.. image:: ../../images/phycore-am57x/pb-057948_hdmi_fbtest_test002.jpg
   :width: 450px
   :alt: phyCORE-AM57x HDMI Test 2
.. image:: ../../images/phycore-am57x/pb-057948_hdmi_fbtest_test004.jpg
   :width: 450px
   :alt: phyCORE-AM57x HDMI Test 4
.. image:: ../../images/phycore-am57x/pb-057948_hdmi_fbtest_test006.jpg
   :width: 450px
   :alt: phyCORE-AM57x HDMI Test 6
.. image:: ../../images/phycore-am57x/pb-057948_hdmi_fbtest_test008.jpg
   :width: 450px
   :alt: phyCORE-AM57x HDMI Test 8
.. image:: ../../images/phycore-am57x/pb-057948_hdmi_fbtest_test009.jpg
   :width: 450px
   :alt: phyCORE-AM57x HDMI Test 9




* Power on the board and boot into Linux.
* An application called the Matrix-GUI will appear on the display.

Controlling the Backlight
-------------------------

The backlight brightness of the display is controlled by a PWM and can be configured via Linux in the sysfs.

* To read the current backlight brightness:

  .. code-block:: none
      :caption: Target (Linux)

      cat /sys/devices/platform/backlight/backlight/backlight/brightness

* Set "brightness" to values 0-7, with 7 being the brightest. For example:

  .. code-block:: none
      :caption: Target (Linux)

      echo 7 > /sys/devices/platform/backlight/backlight/backlight/brightness

* Set bl_power to turn backlight off/on. Valid values are 1 for off and 0 for on:

  .. code-block:: none
      :caption: Target (Linux)

      echo 1 > /sys/devices/platform/backlight/backlight/backlight/bl_power
      echo 0 > /sys/devices/platform/backlight/backlight/backlight/bl_power

  .. note::
    Not seeing the display brightness change? Check the above Note!