IOT-GATE-iMX7 and SBC-IOT-iMX7: Yocto Linux: User Space
Contents
Overview
The example run-time Yocto Linux filesystem image for the IOT-GATE-iMX7 IoT Gateway and SBC-IOT-iMX7 Single Board Computer is based on NXP Community Yocto Project BSP for i.MX based boards.
Creating Live SD-card article provides a brief introduction on how to create and use the live Yocto Live-SD card.
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The article uses cl-rootfs hostname. A real hostname may be different. |
Using Yocto Linux
Connection and Logging In
Use the root username to login:
cl-rootfs login: root
Networking
The networking configuration in the example Yocto Linux image is almost the same as in the Debian Linux image.
Analog Audio
Use aplay -l to list all sound cards and digital audio devices registered on the system:
root@cl-rootfs:~# aplay -l **** List of PLAYBACK Hardware Devices **** card 0: clsomimx7 [cl-som-imx7], device 0: 308a0000.sai-wm8731-hifi wm8731-hifi-0 [] Subdevices: 1/1 Subdevice #0: subdevice #0
Analog Audio Playback
In order to play back a sound file make use of the aplay application.
- aplay -L can be used for listing of all pcm devices.
Here is a sample output of aplay -L command:
root@cl-rootfs:~# aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
default:CARD=clsomimx7
cl-som-imx7,
Default Audio Device
sysdefault:CARD=clsomimx7
cl-som-imx7,
Default Audio Device
dmix:CARD=clsomimx7,DEV=0
cl-som-imx7,
Direct sample mixing device
dsnoop:CARD=clsomimx7,DEV=0
cl-som-imx7,
Direct sample snooping device
hw:CARD=clsomimx7,DEV=0
cl-som-imx7,
Direct hardware device without any conversions
plughw:CARD=clsomimx7,DEV=0
cl-som-imx7,
Hardware device with all software conversions
The next command can be used for audio play back:
root@cl-rootfs:~# aplay -D sysdefault <wav-file>
Audio Input Settings
CL-SOM-iMX7 provides an audio capturing feature from either Mic or Line In input sources. alsamixer or amixer can be used in order to switch between these inputs.
Mic
- alsamixer
- Capture Volume => 100
- Line Capture Switch => off
- Mic Capture Switch => on
- Input Mux => Mic
- amixer
amixer cset numid=1 65536 amixer -c 0 cset numid=3 31,31 amixer -c 0 cset numid=4 0 amixer -c 0 cset numid=6 1 amixer -c 0 cset numid=14 1
Line In
- alsamixer
- Capture Volume => 100
- Line Capture Switch => on
- Mic Capture Switch => off
- Input Mux => Line In
- amixer
amixer cset numid=1 65536 amixer -c 0 cset numid=3 31 amixer -c 0 cset numid=4 1 amixer -c 0 cset numid=6 0 amixer -c 0 cset numid=14 0
Sample Audio Recording
As soon as the correct input values have been set, audio signal can be captured. Here is a sample command that shows the arecord usage for capturing audio signal from the selected input line.
root@cl-rootfs:~# arecord -D sysdefault -d 10 -f dat -t wav /tmp/out.wav
WiFi
CL-SOM-iMX7 features 802.11b/g/n wireless connectivity solution, implemented with a TI WiLink8 Combo module. The device driver name is wl18xx.
By default all wireless interfaces are soft blocked. Use the rfkill utility to block/unblock wireless interfaces and display their status.
WiFi Initialization
- WiFi requires no user interaction for being configured. The driver gets loaded automatically.
Make sure that the WiFi driver is loaded:
root@cl-som-imx7:~# lsmod | grep wl18xx wl18xx 70950 0
The WiFi driver can be loaded manually:
root@cl-som-imx7:~# modprobe wl18xx wlcore: ERROR could not get configuration binary ti-connectivity/wl18xx-conf.bin: -2 wlcore: WARNING falling back to default config wlcore: wl18xx HW: 183x or 180x, PG 2.2 (ROM 0x11) wlcore: loaded
- iwconfig command from wireless-tools package can be used to retrieve detailed information about the WiFi interfaces:
root@cl-som-imx7:~# iwconfig wlan0
wlan0 IEEE 802.11 ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=0 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:on
- Unblock the interface:
root@cl-som-imx7:~# rfkill unblock wifi wlcore: PHY firmware version: Rev 8.2.0.0.236 wlcore: firmware booted (Rev 8.9.0.0.69) IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
- Activate the interface:
root@cl-som-imx7:~# ifconfig wlan0 up
- Sample WiFi scanning:
root@cl-som-imx7:~# iwlist wlan0 scan
The output will show the list of Access Points and Ad-Hoc cells in range. For more information about connecting to wireless networks and tuning WiFi interfaces refer to “wpa_supplicant” and “wireless-tools” man pages.
wpa_supplicant
- Configure wpa_supplicant to connect to SSID with no key management. Put the network name into the "ssid" fields:
root@cl-som-imx7:~# cat << EOF > /etc/wpa_supplicant.conf
ctrl_interface=/var/run/wpa_supplicant
network={
ssid="wireless_network_name"
key_mgmt=NONE
}
EOF
- or with key management. Put the network name and the password into the "ssid/psk" fields:
root@cl-som-imx7:~# cat << EOF > /etc/wpa_supplicant.conf
ctrl_interface=/var/run/wpa_supplicant
network={
ssid="wireless_network_name"
key_mgmt=WPA-PSK
psk="wireless_network_password"
}
EOF
- Sample run
root@cl-som-imx7:~# ifconfig wlan0 up root@cl-som-imx7:~# wpa_supplicant -B -Dwext -c /etc/wpa_supplicant.conf -i wlan0 root@cl-som-imx7:~# dhclient wlan0
