CM-T43: Yocto Linux: User Space

Overview

The example run-time Yocto Linux filesystem image for the CompuLab CM-T43 System-on-Module / Computer-on-Module is based on Texas Instruments Arago project.

The Automatic Installation page provides a brief introduction on how to install the run-time Yocto Linux image.

Using Yocto Linux on CM-T43

Connection and Logging In

Use the following username to login:

root@cm-t43: root

To login into the Linux system, you may use a serial console (ttyO0) at 115200 bps, or connect through the network.

Networking

CM-T43 can operate in two modes: dual MAC mode, or as a 3 port ethernet switch. The default mode of operation is dual MAC mode. A user guide for both operation modes can be found in the Linux Core CPSW User's Guide article in the TI wiki. To configure networking, edit /etc/network/interfaces, /etc/resolv.conf, /etc/hostname and /etc/hosts. For more information about Linux network configuration read Network setup chapter in the Debian Reference.

Switching to 3-port switch mode

To enable 3-port switch mode, the device tree blob must be modified to remove the dual_emac property before Linux boots. This can be done using the following U-Boot commands:

# fdt addr <address fdt was loaded to>
# fdt rm /ocp/ethernet@4a100000 dual_emac

Wayland display server

The Arago root filesystem image contains fully featured display server system Wayland/Weston. Wayland is a protocol that specifies the communication between a display server (called Wayland compositor) and its clients, as well as a reference implementation of the protocol. The Wayland project includes a demo Wayland compositor, called Weston. It's fast, small, and runs on embedded and mobile devices. On start-up Wayland and the Texas Instruments Matrix is started. Connect USB mouse and keyboard for interaction with Wayland and the Texas Instruments Matrix.

Use the following commands to stop the matrix:

/etc/init.d/matrix-gui-2.0 stop

Use the following commands to start the matrix:

/etc/init.d/matrix-gui-2.0 start

Use the following commands to stop the Weston:

/etc/init.d/weston stop

Use the following commands to start the Weston:

/etc/init.d/weston start

Display options

CM-T43 evaluation platform has three video output interfaces: LCD, DVI, and LVDS. Default configuration of Yocto Linux for CM-T43 uses LCD as primary video output.

USB Dual-Role-Device

CM-T43 has USB DWC3 based controller. It features USB 2.0 Dual-Role-Device (DRD) subsystem with integrated HS/FS (USB2.0) PHY. CM-T43 DRD port is USB host and USB device (gadget) capable. USB Device Gadget drivers are compiled as modules with default CM-T43 kernel configuration. Current Linux kernel support of DWC3 features does not allow dynamic role (host/device) switching during runtime. By default, host role is assigned to CM-T43 DRD port.

Device mode can be enabled by running the following U-Boot commands before boot:

# fdt addr <address fdt was loaded to>
# fdt resize
# fdt set /ocp/omap_dwc3@48380000/usb@48390000 dr_mode peripheral

Testing Device (gadget) mode

Default CM-T43 kernel configuration enables g_serial, g_mass_storage, g_ether, g_audio, and g_hid gadget drivers. More gadget drivers can be enabled in the kernel configuration.

Connect USB OTG micro B-cable (ID pin Float) to P3 USB DRD port of SB-SOM baseboard.
Connect other side Standard-A connector to Linux Host PC USB Host port.

Emulate a serial link

Load gadget driver on CM-T43 Eval board:

root@cm-t43:~# modprobe g_serial
[   56.306729] g_serial gadget: Gadget Serial v2.4
[   56.311433] g_serial gadget: g_serial ready
[   56.758367] g_serial gadget: high-speed config #2: CDC ACM config

Ensure the connection is established on the Host PC:

user@linux-host:~$ dmesg
...
[72415.607738] cdc_acm 2-1.8.2:2.0: ttyACM0: USB ACM device
[72415.608446] usbcore: registered new interface driver cdc_acm
[72415.608447] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

Receive data on CM-T43 Eval board:

root@cm-t43:~# cat /dev/ttyGS0

Send data from Host PC:

user@linux-host:~$ echo "Test message" > /dev/ttyACM0

Analog Audio

CM-T43 provides an analog audio interface, which is registered as a standard ALSA sound card. Use aplay -l to list all soundcards and digital audio devices registered on the system:

root@cm-t43:~# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: CMT43SoundCard [CM-T43-Sound-Card], device 0: davinci-mcasp.0-wm8731-hifi wm8731-hifi-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Analog Audio Settings

To enable the Analog audio playback, alsamixer or amixer applications can be used.

alsamixer - set the “Output Mixer” control on.

or

amixer - set the “Output Mixer HiFi Playback Switch” control on using command line interface:

root@cm-t43:/# amixer cset numid=13 1
numid=13,iface=MIXER,name='Output Mixer HiFi Playback Switch'
  ; type=BOOLEAN,access=rw------,values=1
  : values=on

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@cm-t43:/# aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
pulse
    PulseAudio Sound Server
default:CARD=CMT43SoundCard
    CM-T43-Sound-Card, 
    Default Audio Device
sysdefault:CARD=CMT43SoundCard
    CM-T43-Sound-Card, 
    Default Audio Device

WiFi

CM-T43 features 802.11b/g/n wireless connectivity solution, implemented with a Marvell wireless controller module.

WiFi Initialization

The driver gets loaded automatically. Make sure that the WiFi driver is loaded:

root@cm-t43:/# lsmod | grep mwifi
mwifiex_sdio           26039  0
mwifiex               256669  1 mwifiex_sdio
cfg80211              259154  1 mwifiex

iwconfig command from wireless-tools package can be used to retrieve detailed information about the WiFi interfaces:

mlan0     IEEE 802.11abgn  ESSID:off/any  
          Mode:Managed  Access Point: Not-Associated   
          Retry short limit:9   RTS thr=2347 B   Fragment thr=2346 B   
          Encryption key:off
          Power Management:on

WLAN interface activating:

root@cm-t43:/# ifconfig mlan0 up

Sample WiFi scanning:

root@cm-t43:/# iwlist mlan0 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.

Bluetooth

Host Controller Interface (HCI) Initialization

HCI requires no user interaction for being configured. The driver gets loaded automatically unless this option has been disabled by putting a black list rule for this device.

Make sure that the Bluetooth driver is loaded:

root@cm-t43:/# lsmod | grep btmrvl
btmrvl_sdio            14518  0
btmrvl                 12690  1 btmrvl_sdio
bluetooth             326343  16 bnep,btmrvl,btmrvl_sdio

HCI device configuration utility can be run to retrieve detailed information about the Bluetooth interfaces:

root@cm-t43:/# hciconfig -a
hci0:	Type: BR/EDR  Bus: SDIO
	BD Address: 80:D2:1D:5F:45:18  ACL MTU: 1021:7  SCO MTU: 120:6
	UP RUNNING PSCAN 
	RX bytes:1704 acl:0 sco:0 events:76 errors:0
	TX bytes:1459 acl:0 sco:0 commands:75 errors:0
	Features: 0xff 0xfe 0x8f 0xfe 0xdb 0xff 0x7b 0x87
	Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
	Link policy: RSWITCH HOLD SNIFF 
	Link mode: SLAVE ACCEPT 
	Name: 'cm-t43-0'
	Class: 0x000100
	Service Classes: Unspecified
	Device Class: Computer, Uncategorized
	HCI Version:  (0x8)  Revision: 0x8300
	LMP Version:  (0x8)  Subversion: 0x7270
	Manufacturer: Marvell Technology Group Ltd. (72)

If the HCI device is not running, use the below command to enable the HCI device:

root@cm-t43:/# hciconfig hci0 up

HCI inquire remote devices

root@cm-t43:/# hcitool scan
Scanning ...

RTC

Accessing and setting the RTC

To access the RTC time and date run:

root@cm-t43:/# hwclock
Sat Jun 17 13:36:35 2017  0.000000 seconds

To set the date and write it into the RTC do the following:

root@cm-t43:/# date -s "2015-02-11 10:00:00"
Wed Feb 11 10:00:00 UTC 2015
root@cm-t43:/# hwclock -w
root@cm-t43:/# hwclock
Sat Jun 17 13:39:09 2017  0.000000 seconds

Touchscreen

Touchscreen calibration runs on first boot. To rerun it, execute the following commands:

rm /etc/udev/rules.d/ws-calibrate.rules
rm /run/media/mmcblk0p1/ws-calibrate.rules
reboot

CAN bus

Install can-utils using:

# apt-get install can-utils

CAN interface configuration

Load the can bus modules:

root@cm-t43:~# modprobe can-raw
[  123.114470] can: controller area network core (rev 20120528 abi 9)
[  123.120993] NET: Registered protocol family 29
[  123.155278] can: raw protocol (rev 20120528)
root@cm-t43:~# modprobe can-bcm
[  145.749470] can: broadcast manager protocol (rev 20120528 t)

It is recommended configure the CAN interface, with the iproute2 utilities.

To make sure the right ip utility is used, run:

root@cm-t43:~# ip -V
ip utility, iproute2-ss160111

Configure the CAN interface bit-rate to 125 Kbits/sec (values of up to 1Mbit/sec are supported):

root@cm-t43:~# ip link set can0 type can bitrate 125000

Enable the CAN interface:

root@cm-t43:~# ip link set can0 up
[  184.948857] net can0: c_can_hw_raminit_wait_syscon: time out
[  184.954781] c_can_platform 481d0000.can can0: setting BTR=0518 BRPE=0000

Send/Receive packets

Use cansend and candump utilities to send and receive packets via CAN interface.

Send standard CAN frame (on the first device):

root@cm-t43:~# cansend can0 111#1122334455667788

Send extended CAN frame (on the first device):

root@cm-t43:~# cansend can0 11111111#1122334455667788

Dump all received data frames as well as error frames (on the second device):

root@cm-t43:~# candump any,0:0,#FFFFFFFF
  can0  111  [8] 11 22 33 44 55 66 77 88
  can0  11111111  [8] 11 22 33 44 55 66 77 88

GPIO

To use a GPIO:

Select a pin you wish to use as GPIO by consulting the CM-T43 reference manual. The reference manual contains a list of pins and the possible functions each pin can support, many of which include GPIO signals as one of the possible functions.
Setup the pinmux so that the GPIO function is selected for the pin you chose in the previous step. This may require you to edit the device tree for CM-T43. Consult the device tree article in the CM-T43 Linux wiki.
Export the GPIO in Linux sysfs and cd into it

root@cm-t43:/# echo <gpio_num> > /sys/class/gpio/export
root@cm-t43:/# cd gpio<gpio_num>

Select GPIO input/output function:

root@cm-t43:/# echo in > direction

or

root@cm-t43:/# echo out > direction

To read GPIO input (or determine what value is being output):

root@cm-t43:/# cat value
0

To output a value on the GPIO pin:

root@cm-t43:/# echo 1 > value

PRU

CM-T43 Yocto Linux has PRU support. For usage instructions, consult the TI PRU wiki.

CM-T43: Yocto Linux: User Space

Contents

Overview

Using Yocto Linux on CM-T43

Connection and Logging In

Networking

Switching to 3-port switch mode

Wayland display server

Display options

USB Dual-Role-Device

Testing Device (gadget) mode

Emulate a serial link

Analog Audio

Analog Audio Settings

Analog Audio Playback

WiFi

WiFi Initialization

Bluetooth

Host Controller Interface (HCI) Initialization

RTC

Accessing and setting the RTC

Touchscreen

CAN bus

CAN interface configuration

Send/Receive packets

GPIO

PRU

See also

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