VAR-SOM-MX6 Yocto Unit Testing V10 Fido

From Variscite Wiki
Unit Testing



Scan for wireless networks:

$ ifconfig wlan0 up
$ iw dev wlan0 scan | grep SSID

Connecting to a WPA encrypted network:
Find your network from the above scan command.

$ mv /etc/wpa_supplicant.conf /etc/
$ wpa_passphrase <YourAP> <YourPassword> >/etc/wpa_supplicant.conf
$ wpa_supplicant -B -Dnl80211 -iwlan0 -c/etc/wpa_supplicant.conf

wait for:

wlcore: Association completed.

Disable eth0:

$ ifconfig eth0 down


$ udhcpc -iwlan0
$ ifconfig

Useful link for common iw commands:

Access Point

This example will demonstrate you how to use the VAR-SOM-MX6 as an access point. It will forward packets from wlan0 to eth0. DHCPD:

$ vi /etc/udhcpd.conf 
# Sample udhcpd configuration file (/etc/udhcpd.conf)
# The start and end of the IP lease block
start     #default:
end       #default:
# The interface that udhcpd will use
interface   wlan0               #default: eth0
opt     dns # public google dns servers
option  subnet
opt     router
option  lease   864000          # 10 days of seconds

This is a network example. You need to set the IP address based on your network.
First ensure that wpa_supplicant is not holding the device

$ killall wpa_supplicant

IP Forwarding:

$ echo 1 > /proc/sys/net/ipv4/ip_forward
$ ifconfig wlan0
$ hostapd -B /etc/hostapd.conf -P /var/run/
$ udhcpd /etc/udhcpd.conf
$ iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

As a next step one should take a look at /etc/hostapd.conf. You may want to configure password access point name etc.


This phase is not required by default. VAR-SOM-MX6 V2.X (WiLink8):

  • Select your WL183x p/n:
$ cd /usr/bin/wlconf/
$ ./ wl18xx
select one out of : WL1831, WL1833, WL1835, WL1837.

As a result some additional information may be required like 1/2 antenna connected
<reboot system!>

note: In Yocto Dizzy, ignore the following

wl1271_sdio: probe of mmc2:0001:1 failed with error -110
wl1271_sdio: probe of mmc2:0001:2 failed with error -110

First time need to set mac address to be used automatically (Not required in Yocto Dizzy)

$ calibrator set nvs_mac /lib/firmware/ti-connectivity/wl1271-nvs.bin 00:00:00:00:00:00

Gbit Ethernet

On Target:

$ ifconfig
$ iperf -s -u

On Host:

$ iperf -c -u -b400M


$ hcitool scan
$ l2ping 98:03:D8:C7:1A:96

Video playback

Play video file, from linux shell type:

$ gplay <file>

You can also use the "IMX Player" utility to play a movie from the GUI.


$ gst-launch imxv4l2src ! imxv4l2sink

You can also use the "IMX Camera" GUI utility to record and play movie or capture image.

Audio record/play

$ amixer set PCM 125
$ aplay /usr/share/sounds/alsa/Front_Center.wav
$ arecord -f cd -d 10 -D hw:0,0 test.wav
$ aplay test.wav 

Resistive and/or Capacitive touch panel display boot arguments

Variscite expand the default display settings to support alternate display without requirement to change the device tree. During boot we will add screen_alternate=yes to select the second display settings (capacitive display). One can prevent the environment modification of u-boot by settings var_auto_fdt_file=N.

HDMI boot arguments

Choosing HDMI display is determined by passing relevant bootargs from U-BOOT to Kernel.
Add the following arguments in addition to the default ones:

For example HDMI 1080P: If your current settings is booting from SD-Card
In U-boot write :

U-Boot # 'editenv mmcargs' and copy past "video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24" at the end.

As another example, booting from NAND boot args will look like:

U-Boot # 'editenv bootargs ' and copy past " video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24" at the end.

LVDS boot arguments

Resistive/Capacitive alternate screen

Variscite expand the default display settings to support alternate display without any requirement to change the device tree. During the boot sequence Variscite u-boot will add screen_alternate=yes option to enable selection of the second display settings (capacitive display).
For example:

U-Boot # printenv mmcargs
mmcargs=setenv bootargs console=${console},${baudrate} ${smp} video=mxcfb1:off root=${mmcroot} 

The developer can prevent the modification of u-boot by settings var_auto_fdt_file=N.

U-Boot # setenv var_auto_fdt_file=N

Switching to LVDS1 as main display

Switching to LVDS1 display requires changing the "primary" of the lvds section flag in the device tree. Setting display to be LVDS1 by default: edit arch/arm/boot/dts/imx6qdl-var-som.dtsi and set section of the lvds1. When you set the "primary" property to the LVDS1 struct, make sure you remove it from the LVDS0 struct

lvds-channel@1 {
fsl,data-mapping = "spwg";
fsl,data-width = <18>;
crtc = "ipu1-di1";
status = "okay";
display-timings {
native-mode = <&timing1>;
timing1: hsd100pxn1 {
clock-frequency = <35714000>;
hactive = <800>;
vactive = <480>;
hback-porch = <28>;
hfront-porch = <17>;
vback-porch = <13>;
vfront-porch = <20>;
hsync-len = <20>;
vsync-len = <13>;

Please take a look on the wiki section for kernel out of tree to see how to compile the device tree.


$ cd /sys/class/backlight/backlight.X (number changes)
$ echo 0 > brightness 
$ echo 7 > brightness


To set the RTC first set the date from Linux shell, type:

$ date --set="20150225 09:04"

Then set the real time clock from Linux shell, type:

$ hwclock --systohc --utc

Power down your board wait 5 minutes and power up. Check your system with date and the time should be up to date.

External Uart

Use minicom to connect. Set the serial to ttymxc2 You can use a loopback or connect to anther computer


$ $ fdisk /dev/sda 
When you get prompt "Command (m for help):" hit p

Test output example:

root@varsommx6q:~# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST9120823AS      Rev: 3.AD
  Type:   Direct-Access                    ANSI  SCSI revision: 05
root@varsommx6q:~# fdisk /dev/sda

The number of cylinders for this disk is set to 14593.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/sda: 120.0 GB, 120034123776 bytes
255 heads, 63 sectors/track, 14593 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks  Id System
/dev/sda1   *           1        9123    73280466   7 HPFS/NTFS
/dev/sda2            9124       14593    43937744+  f Win95 Ext'd (LBA)
/dev/sda5            9124       11035    15358108+  7 HPFS/NTFS
/dev/sda6           14319       14593     2208906  82 Linux swap
/dev/sda7           11036       14318    26369024  83 Linux

eMMC (SOM version 2.x)

nand-recovery version 34 and 36 supports flashing of eMMC without the requirement of the process below.
  • Check that the device is up.
$ dmesg | grep mmcblk
  • Output example

mmcblk0: mmc1:0001 MBG4GC 29.1 GiB
mmcblk0boot0: mmc1:0001 MBG4GC partition 1 4.00 MiB
mmcblk0boot1: mmc1:0001 MBG4GC partition 2 4.00 MiB
mmcblk0rpmb: mmc1:0001 MBG4GC partition 3 4.00 MiB
mmcblk0: unknown partition table
mmcblk0boot1: unknown partition table
mmcblk0boot0: unknown partition table
Select the eMMC device number. Number will change if SD card is in.

  • Create partition
 $fdisk /dev/mmcblk1
enter n p 1 <enter> <enter> w

Example of a partition root@varsomimx6:~# fdisk /dev/mmcblk1 Device contains neither a valid DOS partition table, nor Sun, SGI, OSF or GPT disklabel Building a new DOS disklabel. Changes will remain in memory only, until you decide to write them. After that the previous content won't be recoverable.

The number of cylinders for this disk is set to 954240. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs

  (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): n Command action

  e   extended
  p   primary partition (1-4)

p Partition number (1-4): 1 First cylinder (1-954240, default 1): Using default value 1 Last cylinder or +size or +sizeM or +sizeK (1-954240, default 954240): Using default value 954240

Command (m for help): p

Disk /dev/mmcblk1: 31.2 GB, 31268536320 bytes 4 heads, 16 sectors/track, 954240 cylinders Units = cylinders of 64 * 512 = 32768 bytes

       Device Boot      Start         End      Blocks  Id System

/dev/mmcblk1p1 1 954240 30535672 83 Linux

Command (m for help): w The partition table has been altered. Calling ioctl() to re-read partition table

mmcblk1: p1
  • Format and mount
$ mkfs.ext3 /dev/mmcblk1p1 
$ reboot


$ lspci 

The output should look like:
00:00.0 PCI bridge: Device 16c3:abcd (rev 01) 01:00.0 Network controller: Intel Corporation PRO/Wireless 4965 AG or AGN [Kedron] Network Connection (rev 61)

USB OTG as host

By default the OTG is configure to be "host". You can switch it to "peripheral" if you change the dr_mode in the device tree.

&usbotg {
	vbus-supply = <&reg_usb_otg_vbus>;
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_usbotg_var>;
	/* dr_mode: One of "host", "peripheral" or "otg". Defaults to "otg" */
	dr_mode = "host" ;
	status = "okay";
  • build Linux out of tree.
  • edit arch/arm/boot/dts/imx6qdl-var-som.dtsi
  • Change the dr_mode in usbotg section
  • re build the device tree with
$ make ARCH=arm CROSS_COMPILE=arm-poky-linux-gnueabi- imx6q-var-som.dtb

copy the file to the sd-card or re flash it to nand. See the relevant section in the WIKI.

USB OTG as device

Plug a cable to a A linux host.

Folow and build the backing_file.

On the Target:

$ modprobe g_mass_storage file=./backing_file

On the Host:

use dmesg and find out your device for example /dev/sdb
$ sudo dd if=/dev/zero of=/dev/sdb bs=128k count=1000

USB Host

Plug a DiskOnKey, Mouse or Keyboard to any of the 3 USB host ports on EVK

GPIO manipulation

Please refer to VAR-SOM-MX6 GPIO

I2C manipulation

Please refer to VAR-SOM-MX6 I2C


Starting Release 4 of the Yocto Canbus is integrated into the system. No patch required.

  1. Connect 2 boards. Each board JP26 connect to the other with the right cable.

Set up the 2 boards by running on each of them:

$ ip link set can0 up type can bitrate 125000

On board #1:

$ cansniffer can0

On board #2:

$ cansend can0 500#1E.10.10


Testing SPI from user space require some changes.

  • Configure your kernel and add spidev driver. Device Drivers -> SPI support -> <*> User mode SPI device driver support
  • Add spidev to your device tree
&ecspi1 {
	fsl,spi-num-chipselects = <1>;
	cs-gpios = <&gpio4 9 0>;
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_ecspi1_2>;
	status = "okay";

        chip1: spidev@0 {
               compatible = "spidev";
               spi-max-frequency = <12000000>;
               reg = <0>;
        chip2: spidev@1 {
               compatible = "spidev";
               spi-max-frequency = <20000000>;
               reg = <1>;

Pick and choose the right chip select and you can also have multiple chip selects.