CL-SOM-AM57x: Linux: Debian

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Overview

The example run-time Linux filesystem image for the CompuLab CL-SOM-AM57x System-on-Module / Computer-on-Module is based on Debian GNU/Linux stretch/sid (armhf).

The default Debian sid Linux image includes many software packages. Among them:

  • Core system
  • Debian package management system
  • X11 Windowing System
  • Fluxbox desktop manager
  • SSH server and client
  • ALSA configuration and usage utilities

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

Using Debian Linux on CL-SOM-AM57x

Connection and Logging In

Use the following username and password to login:

Account with administrative privileges:

cl-debian-armhf login: root
Password: 111111

Regular user account:

cl-debian-armhf login: user	
Password: 111111

To login into the Linux system, you may use a serial console (ttyO2) at 115200 bps, or connect through the network, or use a keyboard and HDMI display.

X Windows system

CompuLab DEMO root filesystem image contains fully featured X server system with Fluxbox window manager. Before starting X server, connect USB mouse and keyboard to the system. You can run X server and Fluxbox window manager by typing startx.

Fluxbox window manager

CL-SOM-AM57x Debian Linux features installed Fluxbox package - a lightweight window manager for the X server system.

  • Fluxbox provides configurable window decorations, a root menu to launch applications and a toolbar that shows the current workspace name, a set of application names and the current time. There is also a workspace menu which allows you to add or remove workspaces. The slit can be used to dock small applications, e.g. most of the bbtools can use slit.
  • Fluxbox can iconify windows to the toolbar, in addition to adding the window to the Icons submenu of the workspace menu.

Visit Fluxbox Wiki and Official home page for more details.

Software Management

Debian Linux image for CL-SOM-AM57x includes all the information required to use Debian package management utilities. You can use apt-get and dpkg out of the box.

Display options

CL-SOM-AM57x evaluation platform has four video output interfaces: HDMI, LCD, DVI, and LVDS. Default configuration of Debian Linux for CL-SOM-AM57x uses HDMI (SB-SOM-AM57x J4 connector) as primary video output.

Touchscreen

CL-SOM-AM57x Evaluation Kit is equipped with Startek KD050C LCD 800x480 LCD touch panel. The touchscreen driver is modularized if you use default CL-SOM-AM57x configuration and is loaded by udev automatically on Linux boot. If the touchscreen driver is not loaded, the following command will load the touchscreen driver:

modprobe ads7846

Touchscreen calibration

A touchscreen device can be calibrated using xinput_calibrator utility.

To calibrate the touchscreen:

  • Update the primary video output to the calibrated display type.
  • Run X Server by issuing startx command
  • Make sure the touchscreen driver is loaded
  • Set the DISPLAY environment variable:
     export DISPLAY=:0
  • Run xinput_calibrator utility. For proper calibration you are required to touch the touchscreen corners and center in the following order: top-left, top-right, bottom-right, bottom-left, center.
  • Create a file /usr/share/X11/xorg.conf.d/99-calibration.conf and paste there a snippet with the calibration results:
root@cl-debian-armhf:~# xinput_calibrator 
	Setting calibration data: 0, 4095, 0, 4095
Calibrating EVDEV driver for "ADS7846 Touchscreen" id=6
	current calibration values (from XInput): min_x=0, max_x=4095 and min_y=0, max_y=4095

Doing dynamic recalibration:
	Setting calibration data: 289, 3781, 3887, 227
	--> Making the calibration permanent <--
  copy the snippet below into '/etc/X11/xorg.conf.d/99-calibration.conf' (/usr/share/X11/xorg.conf.d/ in some distro's)
Section "InputClass"
	Identifier	"calibration"
	MatchProduct	"ADS7846 Touchscreen"
	Option	"Calibration"	"289 3781 3887 227"
	Option	"SwapAxes"	"0"
EndSection

Bluetooth

CL-SOM-AM57x features Bluetooth 4.1 BLE interface. Following sections describe the initialization and simple use cases of Bluetooth device.

Host Controller Interface (HCI) Initialization

  • For TI SDK kernel v4.1.13, create a symbolic link to the bluetooth UART:
root@debian-armhf:~# ln -sf /dev/ttyS9 /dev/ttyO9
  • Attach the ttyO9 serial port to the HCI Bluetooth subsystem:
root@debian-armhf:~# echo "enabled" > /sys/bus/platform/devices/reg-userspace-consumer.0/state
root@debian-armhf:~# hciattach -s 115200 /dev/ttyO9 texas 3000000
Found a Texas Instruments' chip!
Firmware file : /lib/firmware/ti-connectivity/TIInit_11.8.32.bts
Loaded BTS script version 1
texas: changing baud rate to 3000000, flow control to 1
[   89.019183] Bluetooth: Core ver 2.21
[   89.023025] NET: Registered protocol family 31
[   89.027726] Bluetooth: HCI device and connection manager initialized
[   89.034581] Bluetooth: HCI socket layer initialized
[   89.039779] Bluetooth: L2CAP socket layer initialized
[   89.045296] Bluetooth: SCO socket layer initialized
[   89.055192] Bluetooth: HCI UART driver ver 2.3
[   89.059914] Bluetooth: HCI UART protocol H4 registered
[   89.065306] Bluetooth: HCI UART protocol LL registered
[   89.308172] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   89.313747] Bluetooth: BNEP filters: protocol multicast
[   89.319275] Bluetooth: BNEP socket layer initialized
Device setup complete
  • Run HCI device configuration utility to retrieve detailed information about the Bluetooth device:
root@debian-armhf:~# hciconfig -a
hci0:   Type: BR/EDR  Bus: UART
        BD Address: 54:4A:16:13:0D:42  ACL MTU: 1021:6  SCO MTU: 180:4
        UP RUNNING PSCAN 
        RX bytes:704 acl:0 sco:0 events:43 errors:0
        TX bytes:1782 acl:0 sco:0 commands:43 errors:0
        Features: 0xff 0xfe 0x2d 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: 'cl-som-am57x-sid'
        Class: 0x000000
        Service Classes: Unspecified
        Device Class: Miscellaneous, 
        HCI Version: 4.1 (0x7)  Revision: 0x0
        LMP Version: 4.1 (0x7)  Subversion: 0xac08
        Manufacturer: Texas Instruments Inc. (13)
  • If the HCI device is not running, use the below command to enable the HCI device:
root@debian-armhf:~# hciconfig hci0 up
  • HCI Inquire remote devices.
root@debian-armhf:~# hcitool scan
Scanning ...

Bluez5 & PulseAudio

Debian stretch/sid is using BlueZ 5 and PluseAudio 5. BlueZ 5 dropped support for alsa, and uses PulseAudio.
PulseAudio 5 only supports the A2DP profile and not HSP/HFP.

  • Software to install pulseaudio, pulseaudio-module-bluetooth
Install and configure PulseAudio
root@debian-armhf:~# apt-get update
root@debian-armhf:~# apt-get install pulseaudio pulseaudio-module-bluetooth
  • Create a systemd service for running pulseaudio as the pulse user.
root@debian-armhf:~# cat << eof > /etc/systemd/system/pulseaudio.service
[Unit]
Description=Pulse Audio

[Service]
Type=simple
ExecStart=/usr/bin/pulseaudio --system --disallow-exit --disable-shm

[Install]
WantedBy=multi-user.target
eof

root@debian-armhf:~# chown pulse:pulse /etc/systemd/system/pulseaudio.service
  • Create a dbus configuration file for running pulseaudio. Give the pulse user permission to use Bluetooth.
root@debian-armhf:~# cat << eof > /etc/dbus-1/system.d/pulseaudio-bluetooth.conf
<busconfig>

  <policy user="pulse">
    <allow send_destination="org.bluez"/>
  </policy>

</busconfig>
eof

root@debian-armhf:~# chmod 0666 /etc/dbus-1/system.d/pulseaudio-bluetooth.conf
  • Paste the following lines to the end of /etc/pulse/system.pa:
root@debian-armhf:~# cat << eof >> /etc/pulse/system.pa
### Automatically load driver modules for Bluetooth hardware
.ifexists module-bluetooth-policy.so
load-module module-bluetooth-policy
.endif

.ifexists module-bluetooth-discover.so
load-module module-bluetooth-discover
.endif
eof
  • Create /var/run/pulse/.config/pulse directory and fix the ownership.
root@debian-armhf:~# mkdir -p /var/run/pulse/.config/pulse
root@debian-armhf:~# chown -R pulse:pulse /var/run/pulse
  • Add root to the pulse-access,audio groups
root@debian-armhf:~# usermod -a -G pulse-access,audio root
Start PulseAudio
  • Start PulseAudio service
root@debian-armhf:~# systemctl daemon-reload
root@debian-armhf:~# systemctl start pulseaudio.service
  • Make sure that the service is active, running and reports on no error.
root@debian-armhf:~# systemctl status pulseaudio.service
   Loaded: loaded (/etc/systemd/system/pulseaudio.service; disabled)
   Active: active (running) since Mon 2015-07-20 12:00:13 UTC; 1min 34s ago
 Main PID: 805 (pulseaudio)
   CGroup: /system.slice/pulseaudio.service
           └─805 /usr/bin/pulseaudio --system --disallow-exit --disable-shm
Bluez5 pairing

PulseAudio 5.x supports A2DP by default. Make sure the following packages are installed: pulseaudio pulseaudio-module-bluetooth pulseaudio-utils, bluez, bluez-tools.

  • Start the Bluetooth system:
root@debian-armhf:~# systemctl start bluetooth

Now we can use the bluetoothctl command line utility to pair and connect. Run

root@debian-armhf:~# bluetoothctl
[bluetooth]#

to be greeted by its internal command prompt.Then enter:

[bluetooth]# power on
[bluetooth]# agent on
[bluetooth]# default-agent
[bluetooth]# scan on

Make sure that an A2DP device is in pairing mode. It should be discovered shortly. For example,

[NEW] Device 00:07:A4:F2:B3:CB Motorola HT820

shows a device that calls itself "Motorola HT820" and has MAC address 00:07:A4:F2:B3:CB. Use the MAC address to initiate the pairing:

[bluetooth]# pair 00:07:A4:F2:B3:CB

After pairing, connect the device:

[bluetooth]# connect 00:07:A4:F2:B3:CB

After the successful connection, the new output device will be created in PulseAudio.
Scanning can be disabled now:

[bluetooth]# scan off

Exit the program:

[bluetooth]# exit
Playback using PulseAudio
Admolition note.png Next examples assume that the device mac address is 00_07_A4_F2_B3_CB
  • Show the PulseAudio device
root@debian-armhf:~# pactl list cards  | awk '/00_07_A4_F2_B3_CB/' RS=""
Card #1                                                                                                                                                                     
        Name: bluez_card.00_07_A4_F2_B3_CB                                                                                                                                  
        Driver: module-bluez5-device.c                                                                                                                                      
        Owner Module: 13                                                                                                                                                    
        Properties:                                                                                                                                                         
                device.description = "Motorola HT820"                                                                                                                       
                device.string = "00:07:A4:F2:B3:CB"                                                                                                                         
                device.api = "bluez"                                                                                                                                        
                device.class = "sound"                                                                                                                                      
                device.bus = "bluetooth"                                                                                                                                    
                device.form_factor = "headset"                                                                                                                              
                bluez.path = "/org/bluez/hci0/dev_00_07_A4_F2_B3_CB"                                                                                                        
                bluez.class = "0x240404"                                                                                                                                    
                bluez.alias = "Motorola HT820"                                                                                                                              
                device.icon_name = "audio-headset-bluetooth"                                                                                                                
                device.intended_roles = "phone"                                                                                                                             
        Profiles:                                                                                                                                                           
                headset_head_unit: Headset Head Unit (HSP/HFP) (sinks: 1, sources: 1, priority: 20, available: no)
                a2dp_sink: High Fidelity Playback (A2DP Sink) (sinks: 1, sources: 0, priority: 10, available: yes)
                off: Off (sinks: 0, sources: 0, priority: 0, available: yes)
        Active Profile: a2dp_sink
        Ports:
                headset-output: Headset (priority: 0, latency offset: 0 usec)
                        Part of profile(s): headset_head_unit, a2dp_sink
                headset-input: Headset (priority: 0, latency offset: 0 usec, not available)
                        Part of profile(s): headset_head_unit
  • Make sure the active card profile is a2dp_sink. Otherwise switch to it:
# pactl set-card-profile 1 a2dp_sink
  • Show the PulseAudio sink
root@debian-armhf:~# pactl list sinks | awk '/00_07_A4_F2_B3_CB/' RS=""
Sink #1
        State: SUSPENDED
        Name: bluez_sink.00_07_A4_F2_B3_CB
        Description: Motorola HT820
        Driver: module-bluez5-device.c
        Sample Specification: s16le 2ch 48000Hz
        Channel Map: front-left,front-right
        Owner Module: 13
        Mute: no
        Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB
                balance 0.00
        Base Volume: 65536 / 100% / 0.00 dB
        Monitor Source: bluez_sink.00_07_A4_F2_B3_CB.monitor
        Latency: 0 usec, configured 0 usec
        Flags: HARDWARE DECIBEL_VOLUME LATENCY 
        Properties:
                bluetooth.protocol = "a2dp_sink"
                device.description = "Motorola HT820"
                device.string = "00:07:A4:F2:B3:CB"
                device.api = "bluez"
                device.class = "sound"
                device.bus = "bluetooth"
                device.form_factor = "headset"
                bluez.path = "/org/bluez/hci0/dev_00_07_A4_F2_B3_CB"
                bluez.class = "0x240404"
                bluez.alias = "Motorola HT820"
                device.icon_name = "audio-headset-bluetooth"
                device.intended_roles = "phone"
        Ports:
                headset-output: Headset (priority: 0)
        Active Port: headset-output
        Formats:
                pcm
  • Play sound using paplay. Example:
root@debian-armhf:~# paplay -d bluez_sink.00_07_A4_F2_B3_CB /path/to/<audio-file.wav>

Obex FTP service

The OBject EXchange protocol (OBEX) can be used to exchange all kind of objects like files, pictures, calendar entries (vCal) and business cards (vCard) over bluetooth, IrDA, USB and serial cable links.
Use the following command to install file transfer utility for devices that use the OBEX protocol:

root@debian-armhf:~# apt-get update
root@debian-armhf:~# apt-get install obexftp

Following examples demonstrate its usage with mobile phone device.

  • Enable bluetooth on the phone. On CL-SOM-AM57x, scan for available devices to find out phone's BT address:
root@cl-debian-armhf:~# hcitool scan
Scanning ...
	00:15:2A:20:63:94	Nokia 6230i
  • Ensure the phone supports Obex FTP service:
root@cl-debian-armhf:~# sdptool search FTP
Inquiring ...
Searching for FTP on 00:15:2A:20:63:94 ...
Service Name: OBEX File Transfer
Service RecHandle: 0x100de
Service Class ID List:
  "OBEX File Transfer" (0x1106)
Protocol Descriptor List:
  "L2CAP" (0x0100)
  "RFCOMM" (0x0003)
    Channel: 10
  "OBEX" (0x0008)
Language Base Attr List:
  code_ISO639: 0x656e
  encoding:    0x6a
  base_offset: 0x100
Profile Descriptor List:
  "OBEX File Transfer" (0x1106)
    Version: 0x0100
  • Follow the section "Bluez5 pairing" to pair the CL-SOM-AM57x module with the phone.
  • List phone's root folder:
root@cl-debian-armhf:~# obexftp -b 00:15:2A:20:63:94  --list
Browsing 00:15:2A:20:63:94 ...
Connecting..\done
Tried to connect for 579ms
Receiving "(null)".../<?xml version="1.0"?>
<!DOCTYPE folder-listing SYSTEM "obex-folder-listing.dtd"
 [ <!ATTLIST folder mem-type CDATA #IMPLIED> ]>
<folder-listing version="1.0">
    <folder name="EXTENTSION" user-perm="RW" mem-type="MMC"/>
    <folder name="Images" created="19800101T000000" user-perm="R" mem-type="DEV"/>
    <folder name="Video clips" created="19800101T000000" user-perm="R" mem-type="DEV"/>
    <folder name="Music files" created="19800101T000000" user-perm="R" mem-type="DEV"/>
    <folder name="Themes" created="19800101T000000" user-perm="RW" mem-type="DEV"/>
    <folder name="Graphics" created="19800101T000000" user-perm="R" mem-type="DEV"/>
    <folder name="Tones" created="19800101T000000" user-perm="R" mem-type="DEV"/>
    <folder name="Recordings" created="19800101T000000" user-perm="R" mem-type="DEV"/>
</folder-listing>
done
Disconnecting..-done
  • Transfer a file from CL-SOM-AM57x to the phone:
root@cl-debian-armhf:~# obexftp -b 00:15:2A:20:63:94 --put test_file.txt 
Browsing 00:15:2A:20:63:94 ...
Connecting..\done
Tried to connect for 380ms
Sending "test_file.txt"...|done
Disconnecting../done
  • Retrieve a file from the phone to CL-SOM-AM57x:
root@cl-debian-armhf:~# obexftp -b 00:15:2A:20:63:94 --get test_file.txt 
Browsing 00:15:2A:20:63:94 ...
Connecting..\done
Tried to connect for 267ms
Receiving "test_file.txt".../done
Disconnecting..-done

WiFi

CL-SOM-AM57x features 802.11b/g/n wireless connectivity solution, implemented with the TI WiLink 8 WL1801 Wireless controller module.

WiFi Initialization

  • The driver gets loaded automatically. Make sure that the WiFi driver is loaded:
root@cl-debian-armhf:~# lsmod | grep wl
wl18xx                 89863  0 
wlcore                183512  1 wl18xx
mac80211              606845  2 wl18xx,wlcore
cfg80211              491510  3 mac80211,wl18xx,wlcore
wlcore_sdio             6495  0 
  • iwconfig command from wireless-tools package can be used to retrieve detailed information about the WiFi interfaces:
root@cl-debian-armhf:~# iwconfig wlan0
wlan0     IEEE 802.11abgn  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:off
  • WLAN interface activating:
root@cl-debian-armhf:~# ifconfig wlan0 up
[  180.395059] wlcore: PHY firmware version: Rev 8.2.0.0.232
[  180.504299] wlcore: firmware booted (Rev 8.9.0.0.48)
  • Sample WiFi scanning:
root@cl-debian-armhf:~# 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

  • Configuration sample

wpa_supplicant requires a configuration file to be created in order to get connected to a scanned wireless network.
Make use of the example bellow and put the network name and the password into the "ssid/psk" fields.

root@cl-debian-armhf:~# 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-debian-armhf:~# ifconfig wlan0 up
root@cl-debian-armhf:~# wpa_supplicant -B -Dwext -c /etc/wpa_supplicant.conf -i wlan0
root@cl-debian-armhf:~# dhclient wlan0

Controller–area network (CAN)

The CL-SOM-AM57x features a Dual Controller Area Network (DCAN) Modules integrated into Sitara AM57x SoC. The DCAN implements full CAN protocol version 2.0B. It supports both the base (standard) and the extended frame format as well as a programmable data bit rate with maximum of 1Mbit/s.

Loading CAN modules

If the DCAN driver and/or Raw CAN protocol compiled as module(s), they must be loaded prior to enabling CAN interface.

  • Load Raw CAN protocol module:
root@cl-debian-armhf:~# modprobe can-raw
  can: controller area network core (rev 20120528 abi 9)
  NET: Registered protocol family 29
  can: raw protocol (rev 20120528)
CAN interface configuration

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

  • To make sure the right ip utility is used, run:
root@cl-debian-armhf:~# ip -V
  ip utility, iproute2-ss140804
  • Configure the CAN interface bit-rate to 125 Kbits/sec (values of up to 1Mbit/sec are supported):
root@cl-debian-armhf:~# ip link set can0 type can bitrate 125000
  • Enable the CAN interface:
root@cl-debian-armhf:~# ip link set can0 up
  net can0: c_can_hw_raminit_wait_syscon: time out
  c_can_platform 4ae3c000.can can0: setting BTR=1c09 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@cl-debian-armhf:~# cansend can0 111#1122334455667788
  • Send extended CAN frame (on the first device):
root@cl-debian-armhf:~# cansend can0 11111111#1122334455667788
  • Dump all received data frames as well as error frames (on the second device):
root@cl-debian-armhf:~# 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

MMC/SD

The support for MMC/SD card on CL-SOM-AM57x is built into the Linux kernel. To mount the memory card, monitor /proc/partitions to see what partitions were detected on the MMC/SD card. For example, suppose MMC/SD partition you'd like to mount is mmcblk0p1 then:

mkdir -p /mnt/mmcblk0p1 && mount /dev/mmcblk0p1 /mnt/mmcblk0p1

USB 3.0 Dual-Role-Device

CL-SOM-AM57x has USB DWC3 (XHCI) based controller. It features SuperSpeed (SS) USB 3.0 Dual-Role-Device (DRD) subsystem with integrated SS (USB3.0) PHY and HS/FS (USB2.0) PHY. Current Linux kernel support of DWC3 features does not allow dynamic role (host/device) switching in runtime. By default, host role is assigned to CL-SOM-AM57x USB 3.0 port.

RTC

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

root@cl-debian-armhf:~# date -s "31 JUL 2015 10:00:00"
Fri Jul 31 10:00:00 UTC 2015
root@cl-debian-armhf:~# /sbin/hwclock --systohc
root@cl-debian-armhf:~# hwclock -w
Fri Jul 31 10:00:13 2015  -1.066224 seconds

To access the RTC time and date run:

root@cl-debian-armhf:~# hwclock
Fri 31 Jul 2015 10:00:24 AM UTC  -0.083102 seconds

See also