COM iMX6 Linux

FAQ

Ethernet does not work

Check if the line "allow-hotplug eth0" in the file "/etc/network/interfaces" is activated. You can activate the ethernet interface on a running system with the command:

`ifconfig eth0 up`

Remark: To work with a nfs-rootfilesystem you have to disable the line "allow-hotplug eth0" in the file "/etc/network/interfaces". Maybe the system was prepared for this method for development and nobody did change it back.

How to set a Linux environment variable?

This example shows you how to configure the system to use a proxy-server with a environment variable.

`export http_proxy=http://192.168.xxx.xxx:xxxx`

How to schedule jobs to run periodically at certain times or dates?

You can use the cron daemon and/or anacron. To use anacron you have to copy or link your program or script into one of the the following folders:

`/etc/cron.hourly`
`/etc/cron.daily`
`/etc/cron.weekly`
`/etc/cron.monthly`

For further information have a look at the general linux documentation.

Linux virtual machine for development

Introduction

For cross developing of applications we provide virtual machines with preinstalled toolchains. Choose the virtual machine which fits to your DHCOM target (Debian 8 on target -> Debian 8 virtual machine). Debian 8 does include support for architecture armhf and armel (Debian 6 only armel). By default Debian 8 is configured for armhf. The sections Code Examples for Userspace-Applications to Access SPI, I2C, GPIOs, and more and Booting via NFS apply for Debian 6 and Debian 8.

Debian 9 "Stretch" VM image (for VMware and VirtualBox)

Get the virtual machine

Get VMware player or VirtualBox
Debian 9 "Stretch" VMware Image
Default password for devel user: devel
Default password for root user: root

Remark: For security reasons, you must set your own password when starting the virtual machine for the first time:

Enter default user devel password (devel)
Enter default user devel password again (devel)
Enter your own user devel password
Enter your own user devel password again

Version:	File:	Changes:
v2.1.Vx	Debian Stretch v2.1.Vx.zip	- Add Docker - Python updated to version 3.6.9 - Add ARMv7 Cross-Compiler gcc v10.2 - Enable Copy & Paste and Drag & Drop for files
v2.0.Vx	Debian Stretch v2.0.Vx.zip	- First release version of Debian 9 VM

Installed Toolchains

Used for building the Linux Kernel for our ARMv7 DHCOM devices.

ARM GCC 10.2 (available since v2.1.Vx)

armhf: CROSS_COMPILE=/opt/gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf/bin/arm-none-linux-gnueabihf-

ARM GCC 8.3

armhf: CROSS_COMPILE=/opt/gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf/bin/arm-linux-gnueabihf-

Linaro GCC 7.4

armhf: CROSS_COMPILE=/opt/gcc-linaro-7.4.1-2019.02-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-

Linaro GCC 6.3

armhf: CROSS_COMPILE=/opt/gcc-linaro-6.3.1-2017.05-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-

Linaro GCC 4.9

armhf: CROSS_COMPILE=/opt/gcc-linaro-4.9-2014.11-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-

Used for building the Linux Kernel for our ARMv5 DHCOM devices.

CodeSourcery GCC 4.5

armel: CROSS_COMPILE=/opt/CodeSourcery-2011.03-41/bin/arm-none-linux-gnueabi-

Yocto Builds

Note (only concerning v2.0.Vx): If you are going to set up any DH electronics Yocto project by using the repo tool, you need to install Python version 3.6 or later.

This versions are not provided by official Debian Stretch package repositories. To manually install Python 3.6.9 , please follow the instructions:

$: sudo apt install libsqlite3-dev
$: wget https://www.python.org/ftp/python/3.6.9/Python-3.6.9.tgz
$: tar xvf Python-3.6.9.tgz
$: cd Python-3.6.9
$: ./configure --enable-optimizations --enable-shared
$: make -j8
$: sudo make install
$: sudo /sbin/ldconfig -v

Debian 8 "Jessie" VM image (for VMware)

Get the virtual machine

Get the VMware player
Debian 8 "Jessie" VMware Image
Important info (Feb/2018): Don't update the system, because it will brake the cross compiler. If you are asked to upgrade, say NO!
Password for devel user: devel
Password for root user: root

Version:	File:	Changes:
v1.3	Debian Jessie v1.3.zip	- Debian Security updates - Compatibility VMware player 5.0 - Ready for yocto build - Build environment for DHCOM i.MX6 Qt5.7.1 / Qt5.9.1 - Add some useful tools
v1.2	Debian Jessie v1.2.zip	- Debian Security updates - Qt Creator + Support for imx6 modules + Demos - Update elbe to v1.0 - Add some tools / editors
v1.1	Debian Jessie v1.1.zip	- Compatibility VMware player 6.0
v1.0	Debian Jessie v1.0.zip	- New Debian 8 VM

Installed Toolchains

Used for building the Linux Kernel for our ARMv7 DHCOM devices.

Debian Multiarch Cross Toolchain GCC 4.9

armhf: CROSS_COMPILE=arm-linux-gnueabihf-

The Cross Toolchains is preinstalled. They should be used for cross development of native Linux applications. They are downloaded and installed with the Debian Package Manager.

Install directory is /usr/bin/. Please have a look at the preconfigured Examples for cross development using the Eclipse IDE.

Linaro GCC 4.9

armhf: CROSS_COMPILE=/opt/gcc-linaro-4.9-2014.11-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-

Used for building the Linux Kernel for our ARMv5 DHCOM devices.

Debian Multiarch Cross Toolchain

armel: CROSS_COMPILE=arm-linux-gnueabi-

The Cross Toolchains is preinstalled. They should be used for cross development of native Linux applications. They are downloaded and installed with the Debian Package Manager.

Install directory is /usr/bin/. Please have a look at the preconfigured Examples for cross development using the Eclipse IDE.

CodeSourcery GCC 4.5

armel: CROSS_COMPILE=/opt/CodeSourcery-2011.03-41/bin/arm-none-linux-gnueabi-

Qt5 Development

Qt5.5.1 prebuilt and preinstalled

We provide the prebuilt Qt5.5.1 libraries including WebEngine (only QtQuick) and WebKit in /work/qt5/sysroot/. This directory contains a Debian 8 based rootfilesystem which is prepared for DHCOM i.MX6, the matching sysroot (*-dev packages), and the Qt5.5.1 libraries installed.

Qt5.7.1

We support the latest Qt5.7.1 on our DHCOM i.MX6 and DHCOM am335x. Please download and install the qmake-sysroot-mx6-crossarmhf_5.7.1-1.0 or qmake-sysroot-am33-crossarmhf_5.7.1-1.0 package to the DebianVM:

open a terminal
# for i.MX6: wget https://dl.dropboxusercontent.com/u/19433555/DHCOM/imx6/qmake-sysroot-mx6-crossarmhf_5.7.1-1.0_amd64.deb
# for AM335x: wget https://dl.dropboxusercontent.com/u/19433555/DHCOM/am335x/qmake-sysroot-am33-crossarmhf_5.7.1-1.0_amd64.deb
install the package
# sudo dpkg -i qmake-sysroot-mx6-crossarmhf_5.7.1-1.0_amd64.deb
now the sysroot and qmake is ready to use
path to qmake is /work/qt5_mx6_armhf/sysroot/usr/local/qt5.7.1/bin/qmake

Build a Qt5 Application via console

open a terminal
navigate to your Qt5 sources
# /work/qt5/sysroot/usr/local/qt5.5.1/bin/qmake your_own_app.pro
# make

Qt Creator

Start Qt Creator IDE
Open demo project TwoLED: /work/qt5_Demos/TwoLED
There you can find the configurations for your own project.

Debian 6 "Squeeze" VM image (for VMware)

Get the virtual machine

Get the VMware player
Debian Squeeze VMware Image (PW: dhelectronics)
Password for devel user: devel
Password for root user: root

Version:	File:	Changes:
v1.5	Debian Squeeze v1.5pw.zip	- Update VMware Tools - DH UBI-Tools - Language: English - System updates
v1.4	Debian Squeeze v1.4pw.zip	- ELBE v0.3.1 - ELDK 4.2 - Qt Creator 2.6.1 + Qt target libs 4.7.2 - System updates
v1.3	Debian Squeeze v1.3.zipx	- Mono 2.10 - mtd-utils - System updates
v1.2	Debian Squeeze v1.2.zipx	- Emdebian Toolchain gcc 4.3 / g++ 4.3 (`arm-linux-gnueabi-...`) - TortoiseHg + TortoiseHg for Nautilus - Add Plugin "REST Client" in Iceweasel
v1.1	Debian Squeeze v1.1.zipx	- Update Eclipse Indigo with CDT 8.0 - Add demo project "crosshelloworld"
v1.0	Debian Squeeze.zipx	- First Release - CodeSourcery Toolchain (`arm-none-linux-gnueabi-...`) - Eclipse Helios & Indigo

Installed Toolchains

Used for building the Linux Kernel for our ARMv5 DHCOM devices.

Debian Multiarch Cross Toolchain GCC 4.3

armel: CROSS_COMPILE=arm-linux-gnueabi-

The Cross Toolchains is preinstalled. They should be used for cross development of native Linux applications. They are downloaded and installed with the Debian Package Manager.

Install directory is /usr/bin/. Please have a look at the preconfigured Examples for cross development using the Eclipse IDE.

CodeSourcery GCC 4.5

armel: CROSS_COMPILE=/opt/CodeSourcery/Sourcery_G++_Lite/bin/arm-none-linux-gnueabi-

Setting up a Eclipse Cross Executable Project:

Use Eclipse Indigo (version 3.7.1) for your project.
Create a new C++ Project and choose as Executable Project type Cross-Compile Project and as Toolchains Cross GCC
Click the Button "Next" and specify under Tool command path the Toolchain path.

CodeSourcery:

Folder "/opt/CodeSourcery/Sourcery_G++_Lite/bin"

Prefix type "arm-none-linux-gnueabi-"

Emdebian Toolchain:

Folder "/usr/bin"

Prefix type "arm-linux-gnueabi-"

Use Virtualbox instead of VMware Player/Workstation

VMware Maschine mit VirtualBox starten (German)

Booting via TFTP/NFS

Prepare the virtual machine

Setup nfs-kernel-server
- Install thf nfs server: $ sudo apt-get install nfs-kernel-server
- Create a nfsservice directory: $ mkdir /work/nfsroot
- Place the root file system in the folder $ cd /work/nfsroot; sudo tar xf jessie....tar.gz
- Remove network config from rootfs $ rm /work/nfsroot/etc/systemd/network/wired-dhcp.network
- Check whether the line below is part of the /etc/exports file
- /work/nfsroot X.X.X.0/255.255.255.0(rw,no_root_squash,no_subtree_check,insecure)
  - The X must be substituted by our network settings
- Restart the nfs-server with 4 /etc/init.d/nfs-kernel-server restart
Setup tftp-hpa server
- Install a tftp server : $ sudo apt-get install tftpd-hpa
- Create a tftp service directory: $ mkdir /work/tftp
- Edit config: $ sudo vi /etc/default/tftpd-hpa
  - Take care that TFTP_DIRECTORY points to your tftp service directory, for example '/work/tftp'
- Copy Kernel and DeviceTree into the tftp service directory
- Restart the tftp-server with $ /etc/init.d/tftp-hpa restart

Setup the DHCOM Module for TFTP/NFS Boot

This example works with static IP addresses and is tested with DHCOM i.MX6 U-Boot 2015.10 and Kernle 4.4.38. It is possible to work with DHCP, too. For further information see https://www.kernel.org/doc/Documentation/filesystems/nfs/nfsroot.txt

Enter U-Boot console by pressing DEL/BACKSPACE on a RS232 terminal while switching on the power supply of the target
Set IP addresses

`# env set serverip 192.168.178.90` `# env set ipaddr 192.168.178.91`

bootargs for nfs root (up to Debian Jessie)

`# env set rootfs 'root=/dev/nfs nfsroot=192.168.178.90:/work/nfsroot/ ip=192.168.178.91:192.168.178.90::255.255.255.0:dhcom:eth0:none'`

bootargs for nfs root (since Debian Stretch)

`# env set rootfs 'root=/dev/nfs nfsroot=192.168.178.90:/work/nfsroot/,nfsvers=3 ip=192.168.178.91:192.168.178.90::255.255.255.0:dhcom:eth0:none'`

load Linux kernel and devicetree with tftp (change filename and path to match you setup)

`# tftp ${loadaddr} zImage` `# tftp ${fdt_addr} dtbs/imx6dl-dhcom3B-pdk2.dtb`

set bootargs and boot

`# run linuxargs` `# bootz ${loadaddr} - ${fdt_addr}`

optional: save it to be permanent

`# env set bootcmd 'tftp ${loadaddr} zImage; tftp ${fdt_addr} dtbs/imx6dl-dhcom3B-pdk2.dtb; run linuxargs; bootz ${loadaddr} - ${fdt_addr}` `# env save`

Code Examples for Userspace-Applications to Access SPI, I2C, GPIOs, and more

The following code samples are designed to get you started quickly with the device interfaces to SPI, I2C, GPIOs and more in Linux userspace applications.
Within Eclipse you can Import the provided projects:

Execute ">File>Import ..."
Navigate to ">General>Existing Projects into Workspace" within the import dialog
Follow the dialog until you have finished.

Download Code Examples SPI, I2C, GPIOs and more

Included Demos:

SPI
I2C
GPIO
RTC
UART
Watchdog
ADC (only for i.MX25)

Download C++ HAL class library for SPI, I2C, GPIO, UART and physical address space access

For further documentation have a look at http://www.kernel.org/doc/Documentation/.

Building your own Kernel

Sources for the i.MX6 Kernel:

Kernel version: 3.14.12 on GitHub

How to build a kernel:

1. Start the Console on Linux
2. `git clone https://github.com/dh-electronics/linux-imx6qdl.git`
3. `cd linux-imx6qdl`
4. `ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make imx6_dhcom_defconfig`
5. `ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make menuconfig` (optional: If you want to add/remove Kernel features)
6. `ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make dtbs`
7. `ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make zImage`

The built imx6xx-dheva01.dtb device tree files will you find in arch/arm/boot/dts
The built zImage kernel file will you find in arch/arm/boot

Update the kernel with U-Boot

Please refere to the DHCOM Update Mechanism for i.MX6.

Update the kernel in running Linux

1. Copy the kernel zImage file to the path `/boot` 2. Check whether the correct zImage file name is set in `/boot/uLinuxEnv.txt` (e.g. `zImage_file=zImage`) 3. Restart the system (e.g. `reboot`)

Debian Rootfilesystem

Available Rootfilesystems

Please have a look at the iMX6 Downloads section.

Login

`Debian GNU/Linux 6.0 dhcom ttymxc0` `dhcom login: root Password: foo`

Shutdown

`# shutdown -h now`

Calibrating the touchscreen

`# ts_calibrate`

Check the enviroment variable "TSLIB_TSDEVICE=/dev/input/event0" with printenv 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. you can use palimpsest) with Master Boot Record partition scheme

P1: ext3, name="boot" (Primary partition: 100MiB)
P2: ext3, name="rootfs" (Primary partition: Residual space)

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)

Start the Console on Linux
`su`
`chmod 755 /path/of/the/microSD_card`
`cd /path/of/the/microSD_card`
`tar xfjv path/to/RootFS/Name_of_RootFS_file.tar.bz2`

Remark: If you got a *.tar.gz file so type tar xfzv ... to extract the rootfilesystem.

Kernel Userspace Interfaces to Access Hardware

Serial (UART) Interfaces

DHCOM (FF) UART 1	`/dev/ttymxc0`
DHCOM (BT) UART 2	`/dev/ttymxc4`
DHCOM (STD) UART 3	`/dev/ttymxc3`

I2C Interfaces

DHCOM I2C 1	`/dev/i2c-0`
DHCOM I2C 2	`/dev/i2c-1`
On Module Devices	`/dev/i2c-2`

SPI Interfaces

DHCOM SPI 1	`/dev/spidev0.2`
DHCOM SPI 2	`/dev/spidev1.0`

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 i.MX6 doesn‘t boot with the current schematic.

MMC/SD/eMMC Interfaces

DHCOM SD-Interface	`/dev/mmcblk0pX`
on module µSD Card	`/dev/mmcblk1pX`
on module eMMC	`/dev/mmcblk2pX`

'X' has to be replaced with the partition number

Control the display brightness

Coming soon

Control GPIOs

DHCOM Name:	alt. DHCOM Name:	SO-DIMM Pin#	Linux <GPIO#>
GPIO A		154	2
GPIO B		156	4
GPIO C		162	5
GPIO D		163	163
GPIO E		164	101
GPIO F		165	116
GPIO G		167	91
GPIO H		173	103
GPIO I		175	104
CIF HSYNC	GPIO J	74	174
CIF PCLK	GPIO K	72	175
CIF MCLK	GPIO L	70	105
CIF VSYNC	GPIO M	68	192
CIF D9	GPIO N	66	193
CIF D8	GPIO O	64	149
CIF D7	GPIO P	62	205
CIF D6	GPIO Q	60	18
CIF D5	GPIO R	58	16
CIF D4	GPIO S	56	17
CIF D3	GPIO T	54	19
CIF D2	GPIO U	52	20
CIF D1	GPIO V	50	146
CIF D0	GPIO W	48	147

Remark: Depending on your board configuration some of the additional gpios shared with the camera interface are not available on your system.

Export

`echo <GPIO#> >/sys/class/gpio/export`

Remark: Have a look into /sys/class/gpio/ for already configured gpios.

Set direction

`echo in >/sys/class/gpio/gpio<GPIO#>/direction`
`echo out >/sys/class/gpio/gpio<GPIO#>/direction`

Set state

`echo 0 >/sys/class/gpio/gpio<GPIO#>/value`
`echo 1 >/sys/class/gpio/gpio<GPIO#>/value`

Initialize and Test CAN Interface

Initialize:

`ip link set can0 up type can bitrate 500000`

Send test message via cansend (part of can-utils):

`cansend can0 100#11.2233.44556677.88`

Receive can messages (part of can-utils):

`candump can0`

Get can-utils:

Debian package containing can-utils (ARM)

Parallel Address- / Databus

To use the 16-bit address / databus from Linux userspace you can use the UIO driver interface. To enable and configure the interface it is necessary to setup the i.MX6 WEIM controller with the device tree. See the documentation of the device tree bindings of weim here.

Here is an example code which demonstrates how to do enable and configure the WEIM interface (parallel address- / databus):


&weim {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_weim_dhcom_1 &pinctrl_weim_cs0_1>;
    #address-cells = <2>;
    #size-cells = <1>;
    /* it is necessary to setup 2x 64MB otherwise setting gpr fails */
    ranges = <0 0 0x08000000 0x04000000>, // Chipselect A
             <1 0 0x0c000000 0x04000000>; // Chipselect B
    fsl,weim-cs-gpr = <&gpr>;
    status = "okay";
   
        /* use CS 0 */
        uio_pdrv_genirq@0,0 {
        compatible = "generic-uio";
        reg = <0 0x00000000 0x02000000>,
              <0 0x02000000 0x02000000>;
        reg-names = "mem_cs0_first_map", "mem_cs0_second_map";
        #address-cells = <1>;
        #size-cells = <1>;
        fsl,weim-cs-timing = <0x00610089 0x00001002 0x0F011061
                              0x00000000 0x0F068A31 0x00000000>;
    };
};

We have already written some demo code at /arch/arm/boot/dts/imx6qdl-dhcom-weim.dtsi. It is easy to enable in the matching device-tree file:


- // #include "imx6qdl-dhcom-weim.dtsi" // enables WEIM example config with UIO-Driver, 
+ #include "imx6qdl-dhcom-weim.dtsi" // enables WEIM example config with UIO-Driver

To use the generic uio driver it has to be enabled in the kernel configuration (make menuconfig)

Device Drivers -> Userspace I/O Drivers -> Userspace I/O platform driver with generic IRQ handling

The device-tree of_id of the uio driver has to be set via kernel command line

Add "optargs='uio_pdrv_genirq.of_id=generic-uio'" to uLinuxEnv.txt

Example for a UIO userspace driver:

uio_access.cpp
for further information have a look at the paper Userspace I/O drivers in a realtime context

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 /arch/arm/boot/dts/imx6qdl-dheva01.dtsi

Where in the file?

Parallel display:	`display@di0`
LVDS display:	`&ldb`
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:


 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>;
   };
 };

2. Build the device tree dtb files ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- make dtbs

3. Copy the dtb files onto your boot partition /dtbs (SD, µSD or eMMC)

The built imx6xx-dheva01.dtb device tree files will you find in arch/arm/boot/dts

COM iMX6 Linux

FAQ

Ethernet does not work

How to set a Linux environment variable?

How to schedule jobs to run periodically at certain times or dates?

Linux virtual machine for development

Introduction

Debian 9 "Stretch" VM image (for VMware and VirtualBox)

Get the virtual machine

Installed Toolchains

Yocto Builds

Debian 8 "Jessie" VM image (for VMware)

Get the virtual machine

Installed Toolchains

Qt5 Development

Qt5.5.1 prebuilt and preinstalled

Qt5.7.1

Build a Qt5 Application via console

Qt Creator

Debian 6 "Squeeze" VM image (for VMware)

Get the virtual machine

Installed Toolchains

Setting up a Eclipse Cross Executable Project:

Use Virtualbox instead of VMware Player/Workstation

Booting via TFTP/NFS

Prepare the virtual machine

Setup the DHCOM Module for TFTP/NFS Boot

Code Examples for Userspace-Applications to Access SPI, I2C, GPIOs, and more

Building your own Kernel

Sources for the i.MX6 Kernel:

How to build a kernel:

Update the kernel with U-Boot

Update the kernel in running Linux

Debian Rootfilesystem

Available Rootfilesystems

Login

Shutdown

Calibrating the touchscreen

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

Kernel Userspace Interfaces to Access Hardware

Serial (UART) Interfaces

I2C Interfaces

SPI Interfaces

MMC/SD/eMMC Interfaces

Control the display brightness

Control GPIOs

Initialize and Test CAN Interface

Parallel Address- / Databus

Configure your own display

Additional Information

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