View source for COM AM335x Linux

== Linux virtual machine for development ==
* Please have a look at: '''[[Virtual Machine for Application Development]]'''

==Linux Kernel ==

==== Sources for the DHCOM AM335x Linux Kernel v4.1.x ====
:* The latest Linux Kernel source code is available on GitHub: [https://github.com/dh-electronics/linux-am33x https://github.com/dh-electronics/linux-am33x]

==== How to build a Kernel ====
{| class="wikitable" align="center" |  style="width: 100%; background: #f3f3f3;" valign="top" |
|
Get sources from Github
{| class="wikitable" style="width: 100%; color: #000000; background: #ffffff;" |
| 
1. Start a terminal on Linux<br/>
2. <tt># ''git clone [https://github.com/dh-electronics/linux-am33x.git https://github.com/dh-electronics/linux-am33x.git]''</tt><br/>
3. <tt># ''cd linux-am33x''</tt><br/>
4. <tt># ''git checkout release/20160219'' # checkout latest/required release branch</tt>
|}
Configure and build the kernel using 5 threads in a separate build directory
{| class="wikitable" style="width: 100%; color: #000000; background: #ffffff;" |
| 
5. <tt># ''mkdir ../build''</tt><br/>
6. <tt># ''ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make O=../build/ am335x_dhcom_defconfig''</tt><br/>
7. <tt># ''ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make O=../build/ menuconfig''</tt> (optional: Add/Remove Kernel Features)<br/>
8. <tt># ''ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make -j5 O=../build/ zImage''</tt><br/>
9. <tt># ''ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make -j5 O=../build/ dtbs''</tt><br/>
|}
* Your new <tt>zImage</tt> file is available in <tt>../build/arch/arm/boot</tt>
* The Devicetree file <tt>am335x-dheva01.dtb</tt> is available in <tt>../build/arch/arm/boot/dts</tt>
|}

=== Update the Kernel and Devicetree with U-Boot ===
Please refere to the [[DHCOM Update Mechanism |DHCOM Update Mechanism for am335x]].

=== Update Kernel and Devicetree on a running Linux ===
{| class="wikitable" align="center" |  style="width: 100%; background: #f3f3f3;" valign="top" |
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==== Kernel ====
{| class="wikitable" style="width: 100%; color: #000000; background: #ffffff;" |
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'''1.''' Copy the kernel zImage file to the path <tt>'''/boot'''</tt><br/>
'''2.''' Check whether the correct zImage file name is set in <tt>'''/boot/uLinuxEnv.txt'''</tt> (e.g. <tt>'''zImage_file=zImage'''</tt>)<br/>
|}
==== Devicetree ====
{| class="wikitable" style="width: 100%; color: #000000; background: #ffffff;" |
|
'''3.''' Copy the devicetree file am335x-dheva01.dtb to the path <tt>'''/boot/dtbs'''</tt><br/>
'''4.''' Check '''fdtfile''' variable in <tt>'''/boot/uLinuxEnv.txt'''</tt> (e.g. <tt>'''fdtfile=/dtbs/am335x-dheva01.dtb'''</tt>)<br/>
|}
==== Reboot System ====
{| class="wikitable" style="width: 100%; color: #000000; background: #ffffff;" |
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'''5.''' Restart the system (e.g. <tt>'''reboot'''</tt>)
|}
|}

==Debian Rootfilesystem ==

=== Available Rootfilesystems ===
Please have a look at the [[COM_AM335-D2#Downloads | DHCOM AM335x Downloads]] section.

=== External Documentation ===
*  [https://debian-handbook.info/browse/stable/ The Debian Administrator's Handbook]: A reference book presenting the Debian distribution, from initial installation to configuration of services. The administration and configuration chapters apply to our Debian based root filesystems.
*  [https://www.debian.org/doc/ Debian Documentation]

=== Login ===
{| class="wikitable" align="center" |  style="width: 450px; color: #000000; background: #FFFFFF;" valign="top" |
||
<tt>
Debian GNU/Linux 8 dhcom ttyO0<br/>

dhcom login: '''root'''<br/>
Password: '''foo'''
</tt>
|}

=== Shutdown ===
{| class="wikitable" align="center" |  style="width: 450px; color: #000000; background: #FFFFFF;" valign="top" |
|<tt># shutdown -h now</tt>
|}

=== Calibrating the touchscreen (tslib has to be installed) ===
{| class="wikitable" align="center" |  style="width: 450px; color: #000000; background: #FFFFFF;" valign="top" |
|
<tt># source setup_tslib.sh </tt>      # setup environment for use of tslib<br/>
<tt># ts_calibrate</tt>
|}
*Check the enviroment variable "TSLIB_TSDEVICE=/dev/input/event0" with <tt> printenv </tt> if an error occurs.

== How to create a microSD-card with a rootfilesystem on it ==

1. Format a microSD card like following (in linux e.g. gparted, palimpsest) with '''Master Boot Record''' partition scheme
{| class="wikitable" | style="width: 450px; color: #000000; background: #FFFFFF;" valign="top" |
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<tt>P1 '''ext3''', name="boot" (Primary partition: 100MiB)</tt><br/>
<tt>P2 '''ext3''', name="rootfs" (Primary part.: Residual space)</tt>
|}
2. Untar the root file system to the "rootfs" partition of the microSD card (Don't copy the tar archive directly to the microSD card)
{| class="wikitable" | style="width: 450px; color: #000000; background: #FFFFFF;" valign="top" |
|
Start the Console on Linux<br/>
<tt># ''su''</tt><br/>
<tt># ''chmod 755 /path/of/the/microSD_card''</tt><br/>
<tt># ''cd /path/of/the/microSD_card''</tt><br/>
<tt># ''tar xfjv path/to/RootFS/Name_of_RootFS_file.tar.bz2''</tt>
|}
'''Remark:''' If you got a *.tar.gz file so type <tt> tar xfzv ...  </tt> to extract the rootfilesystem.

== Kernel Userspace Interfaces to Access Hardware == 

=== Serial (UART) Interfaces ===
:{| class="wikitable" style="width: 400px"
 ||DHCOM UART 1 (Rx Tx Rts Cts)||<code>/dev/ttyO0</code>
 |-
 ||DHCOM UART 2 (Rx Tx) ||<code>/dev/ttyO1</code>
 |-
 ||DHCOM (STD) UART 3 || not available
 |}

=== I2C Interfaces ===
:{| class="wikitable" style="width: 400px"
 ||DHCOM I2C 1||<code>/dev/i2c-2</code>
 |-
 ||DHCOM I2C 2 || not available
 |-
 ||On Module Devices ||<code>/dev/i2c-0</code>
 |}


=== SPI Interfaces ===
:{| class="wikitable" style="width: 400px"
 ||DHCOM SPI 1||<code>/dev/spidev1.1</code>
 |-
 ||DHCOM SPI 2 || not available
 |}

:: '''Remark:''' DHCOM SPI1 interface doesn‘t work with DHCOM Premium Developer Kit (HD00013).
::Reason: At DHCOM Premium Developer Kit SPI 1 isn‘t connected, because otherwise AM335x doesn‘t boot with the current schematic.

=== MMC/SD/eMMC Interfaces ===
:{| class="wikitable" style="width: 400px"
 ||DHCOM SD-Interface ||<code>/dev/mmcblk0pX</code> (optional)
 |-
 ||on module µSD Card ||<code>/dev/mmcblk0pX</code> (optional)
 |-
 ||on module eMMC ||<code>/dev/mmcblk1pX</code>
 |}

: 'X' has to be replaced with the partition number
: DHCOM SD-Interface '''or''' on module µSD slot is available

=== Control the display brightness ===
:{|class="wikitable" style="width: 600px"
|-
|echo [0..8] > /sys/class/backlight/backlight/brightness
|}

=== Control GPIOs ===
:{|class="wikitable" style="text-align: center; width: 600px"
|-
! DHCOM Name: !! alt. DHCOM Name: !! SO-DIMM Pin# !! Linux <GPIO#> 
|-
| GPIO A || || 154 || 20 
|-
| GPIO B || || 156 || 115 
|-
| GPIO C || || 162 || 116
|-
| GPIO D || || 163 || 65 
|-
| GPIO E || || 164 || 114
|-
| GPIO F || || 165 || 112 
|-
| GPIO G || || 167 || 111
|-
| GPIO H || || 173 || 7 
|-
| GPIO I || || 175 || 113 
|-
| CIF HSYNC || GPIO J || 74 || 117 
|-
| CIF PCLK || GPIO K || 72 || 57
|-
| CIF MCLK || GPIO L || 70 || 56 
|-
| CIF VSYNC || GPIO M || 68 || 55 
|-
| CIF D9 || GPIO N || 66 || 54
|-
| CIF D8 || GPIO O || 64 || 51 
|-
| CIF D7 || GPIO P || 62 || 50 
|-
| CIF D6 || GPIO Q || 60 || 49
|}
:: '''Remark:''' The parallel camera interface is not available on DHCOM AM335x.

:Export
:{| class="wikitable"
|<code>''echo <GPIO#> >/sys/class/gpio/export''</code>
|}
:: '''Remark:''' Have a look into <code> /sys/class/gpio/ </code> for already configured gpios.
:Set direction
:{| class="wikitable"
|<code>''echo in >/sys/class/gpio/gpio<GPIO#>/direction''</code>
|-
|<code>''echo out >/sys/class/gpio/gpio<GPIO#>/direction''</code>
|}

:Set state
:{| class="wikitable"
|<code>''echo 0 >/sys/class/gpio/gpio<GPIO#>/value''</code>
|-
|<code>''echo 1 >/sys/class/gpio/gpio<GPIO#>/value''</code>
|}

=== Initialize and Test CAN Interface ===
:Initialize:
:{| class="wikitable"
|<code>''ip link set can0 up type can bitrate 500000''</code>
|}
 
:Send test message via cansend (part of can-utils):
:{| class="wikitable"
|<code>''cansend can0 100#11.2233.44556677.88''</code>
|}

:Receive can messages (part of can-utils):
:{| class="wikitable"
|<code>''candump can0''</code>
|}

:Get can-utils:
:* [[media:can-utils_armel.zip|Debian package containing can-utils (ARM)]]

=== Configure your own display ===

:To configure your own display you have to do the following steps:

:1. Type in the display values into the device tree file <code>[https://github.com/dh-electronics/linux-imx6qdl/blob/master/arch/arm/boot/dts/imx6qdl-dheva01.dtsi /arch/arm/boot/dts/imx6qdl-dheva01.dtsi]</code>
::*Where in the file?

:::{|
 |style="width: 8em"|Parallel display:||<code>display@di0</code>
 |-
 |style="width: 8em"|LVDS display:||<code>&ldb</code>
 |-
 |colspan="2"|Remarks: If you don't want to use both interfaces comment the unwanted out! The frame buffer resolution depends on the higher display resolution of both displays 
 |}

::*How?
:::Here is an example:
:::{|
|<code>
  display-timings {
    DataImage_7inch_FG0700G3DSSW {
    clock-frequency = <33260000>;
    hactive = <800>;
    vactive = <480>;
    hback-porch = <86>;
    hfront-porch = <42>;
    vback-porch = <33>;
    vfront-porch = <10>;
    hsync-len = <128>;
    vsync-len = <2>;
    hsync-active = <0>;
    vsync-active = <0>;
    de-active = <1>;
    pixelclk-active = <1>;
    };
  };
</code>
|}
:2. Build the device tree dtb files <code>ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make dtbs</code>
:3. Copy the dtb files onto your boot partition <code>/dtbs</code> (SD, µSD or eMMC)
:The built <code>imx6xx-dheva01.dtb</code> device tree files will you find in <code>arch/arm/boot/dts</code>

== Additional Information ==
*[[Linux Kernel Features | Linux Kernel Features ]]
*[[ELBE Overview| Embedded Linux Build Environment (ELBE)]]