CM-T3517: Linux: Debian

Overview

The example run-time Linux filesystem image for CM-T3517 is based on Debian GNU/Linux Sid. The CompuLab Linux package for CM-T3517 includes ready to run NAND flash image, Linux kernel configuration and source code patches and an archive of the root filesystem, used to create the image.

The default Debian Sid Linux image includes more than 400 software packages. Among them:

Core system
Debian package management system
X11 Windowing System
Fluxbox desktop manager
Netsurf web browser
Samba connectivity suite
SSH and FTP server and client
ALSA configuration and usage utilities
CAN Bus utilities
Bluetooth tools and daemons
The Graphics SDK including the Linux graphics (SGX) drivers and ready to run SGX functionality demos

The Getting started with Linux on CM-T3517 page provides a brief introduction on how to install the run-time Linux image. This article describes package structure and peripheral device options specific to the CM-T3517.

Package contents

version.txt

The contents of the version.txt identifies the package version.

images

uImage-cm-t3517 - ready to run Linux kernel image binary for CM-T3517
debian-image.ubi - ready to run Debian Linux UBI image for installation onto the NAND flash
debian-image.tar.bz2 - archive of the Debian root file system
kernel.img - Kernel image required for NAND image installation
ramdisk.img - Ramdisk image required for NAND image installation
bootscr.img - U-Boot script used for image installation

kernel

uImage-3.5.7-cm-t3517-2.bin - ready to run Linux kernel version 3.5.7-cm-t3517-2 for CM-T3517
linux-3.5.7-cm-t3517-2.config - Linux kernel 3.5.7-cm-t3517-2 configuration file
linux-3.5.7-cm-t3517-2.patch - patch vs. Linux stable kernel 3.5.7 with support for CM-T3517 peripherals
patches - ordered collection of patches, that form the single patch above (linux-3.5.7-cm-t3517-2.patch)

utilities

The utilities directory contains miscellaneous utilities useful for development

tftpd32.zip - TFTP server for Windows users
eeprom-util - CompuLab EEPROM utility for reading information found inside the EEPROM on CompuLab boards
bootscr.src - U-Boot script source used for loading kernel and ramdisk images from MMC/SD card
debian-image.cfg - configuration file used by ubinize utility for debian-image.ubi generation. For more information about UBIFS images please refer to the Linux Development for ARM modules article.

extra

The extra directory contains files that are not directly connected to the Linux kernel

Graphics_SDK_04.06.00.03 - directory contains graphics (SGX) related files:

graphics_sdk_04.06.00.03-cm-t3517-2.patch - patch to fix the Graphics SDK v04.06.00.03 compile time errors

Using Debian Linux on CM-T3517

Connection and Logging In

Use the following usernames and passwords to login:

Account with administrative privileges:

User: root
Password: 111111

Regular user account:

User: user	
Password: 111111

In addition to these accounts CM-T3517 allows anonymous FTP access. 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 DVI/LCD display (tty1, tty2, tty3).

Networking

To configure networking, edit /etc/network/interfaces, /etc/udev/rules.d/70-persistent-net.rules, /etc/resolv.conf, /etc/hostname and /etc/hosts. For more information about Debian Linux network configuration read Network setup chapter in the Debian Reference.

Consoles

Linux file system image is designed to suit different kernel versions and configurations. Therefore, during the operating system startup, consoles at several serial ports and DVI display are enabled. Some of these devices may not be supported, either because of kernel versions incompatibilities, or because the kernel was not configured to support these devices. When the console is enabled for such a device, the following or similar message can appear on active console:

INIT: Id "T0" respawning too fast: disabled for 5 minutes

This is not an error message, it is just a warning that can be eliminated by editing /etc/inittab file.

X Windows system

CompuLab distribution contains full featured X Windows system with Fluxbox window manager. Before starting X Windows, connect USB mouse and keyboard to the system. You can run X Windows by typing startx.

Software Management

Debian Linux image for CM-T3517 includes all the information required to use Debian package management utilities. You can use apt-get and dpkg out of the box.

Audio

CM-T3517 uses the TLV320AIC23B (TI) audio codec. If the default CM-T3517 configuration is used, the audio drivers are modularized and are loaded automatically in the boot process.

Codec driver snd_soc_tlv320aic23 must be loaded before audio driver snd-soc-cm-t3517. A workaround could be adding snd-soc-cm-t3517 entry into /etc/modprobe.d/alsa-base-blacklist.conf and /etc/modules.

More information about Linux audio subsystem can be found at ALSA project official website.

Touchscreen

CM-T3517 uses the TSC2046 (TI) touchscreen controller. The touchscreen driver is modularized if you use default CM-T3517 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

The X Windows system of CM-T3517 uses tslib X server input driver to get the input from the touchscreen.

Touchscreen calibration

Touchscreen calibration can be performed with ts_calibrate utility available in package libts-bin. To calibrate the touchscreen:

Make sure X Server is not running
Make sure the touchscreen driver is loaded as described in Touchscreen section
Set the TSLIB_TSDEVICE system variable:

export TSLIB_TSDEVICE=/dev/input/by-path/platform-omap2_mcspi.1-event

Run ts_calibrate 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. The calibration results are saved to file /etc/pointercal.
Use ts_test utility to test the calibration results.

MMC/SD

The support for MMC/SD card on CM-T3517 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:

if [ ! -d /mnt/mmcblk0p1 ]; then mkdir /mnt/mmcblk0p1; fi
mount /dev/mmcblk0p1 /mnt/mmcblk0p1

Controller–area network (CAN)

The CM-T3517 features a TI High End CAN Controller (HECC), integrated into the Sitara AM3517/05 SoC. The TI HECC 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 TI HECC 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@cm-debian:~# modprobe can-raw
can: controller area network core (rev 20090105 abi 8)
NET: Registered protocol family 29
can: raw protocol (rev 20090105)
root@cm-debian:~#

Load TI HECC driver module:

root@cm-debian:~# modprobe ti_hecc
CAN device driver interface
TI High End CAN Controller Driver 0.7
ti_hecc ti_hecc.1: device registered (reg_base=d0a08000, irq=24)
root@cm-debian:~#

For information on enabling CAN kernel support, please, see the Linux Kernel for CM-T3517 page.

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@cm-debian:~# ip -V
ip utility, iproute2-ss100224
root@cm-debian:~#

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

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

Enable the CAN interface:

root@cm-debian:~# ip link set can0 up
ti_hecc ti_hecc.1: setting CANBTC=0xc0028
root@cm-debian:~#

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-debian:/usr/local/can-utils# cansend can0 111#1122334455667788
root@cm-debian:/usr/local/can-utils#

Send extended CAN frame (on the first device):

root@cm-debian:/usr/local/can-utils# cansend can0 11111111#1122334455667788
root@cm-debian:/usr/local/can-utils#

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

root@cm-debian:/usr/local/can-utils# 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

USB On-The-Go (OTG)

CM-T3517 features a Mentor Graphic's USB OTG2.0 high-speed USB On-The-Go (OTG) controller. CM-T3517 OTG port is USB host and USB device (gadget) capable.

Host and Gadget drivers are compiled as modules with default CM-T3517 kernel configuration. Both should be loaded for OTG support.

Load Host driver:

root@cm-debian:~# modprobe am35x
musb-hdrc: version 6.0, ?dma?, otg (peripheral+host)
<6>Waiting for PHY clock good...
musb-hdrc musb-hdrc: >USB OTG mode controller at d0eca000 using PIO, IRQ 71
root@cm-debian:~#

Load Gadget driver:

root@cm-debian:~# modprobe g_serial
 gadget: >Gadget Serial v2.4
 gadget: >g_serial ready
musb-hdrc musb-hdrc: >MUSB HDRC host driver
musb-hdrc musb-hdrc: >new USB bus registered, assigned bus number 2
usb usb2: >New USB device found, idVendor=1d6b, idProduct=0002
usb usb2: >New USB device strings: Mfr=3, Product=2, SerialNumber=1
usb usb2: >Product: MUSB HDRC host driver
usb usb2: >Manufacturer: Linux 3.5.7-cm-t3517+ musb-hcd
usb usb2: >SerialNumber: musb-hdrc
hub 2-0:1.0: >USB hub found
hub 2-0:1.0: >1 port detected
root@cm-debian:~#

Default CM-T3517 kernel configuration enables g_serial, g_mass_storage, g_ether and g_zero gadget drivers. More gadget drivers can be enabled in the kernel configuration.

Testing OTG port

Host mode. Connect USB keyboard to OTG port.

usb 2-1: >new low-speed USB device number 3 using musb-hdrc
usb 2-1: >device v413c p2107 is not supported
usb 2-1: >New USB device found, idVendor=413c, idProduct=2107
usb 2-1: >New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 2-1: >Product: Dell USB Entry Keyboard
usb 2-1: >Manufacturer: Dell
input: Dell Dell USB Entry Keyboard as /devices/platform/musb-am35x/musb-hdrc/usb2/2-1/2-1:1.0/input/input4
hid-generic 0003:413C:2107.0004: >input: USB HID v1.10 Keyboard [Dell Dell USB Entry Keyboard] on usb-musb-hdrc-1/input0

Gadget mode. Connect desktop PC to OTG port.

gadget: >high-speed config #2: CDC ACM config

Bluetooth

CM-T3517 features Bluetooth 4.0 interface. Following sections describe the initialization and simple use cases of Bluetooth device.

Host Controller Interface (HCI) Initialization

Attach the ttyO1 serial UART to the HCI Bluetooth stack:

root@cm-debian:~#  hciattach -s 115200 /dev/ttyO1 texas 3000000
Found a Texas Instruments' chip!
Firmware file : /lib/firmware/TIInit_7.6.15.bts
Loaded BTS script version 1
texas: changing baud rate to 3000000, flow control to 1
Bluetooth: HCI UART driver ver 2.2
Bluetooth: HCI H4 protocol initialized
Bluetooth: HCI BCSP protocol initialized
Bluetooth: HCILL protocol initialized
Bluetooth: RFCOMM TTY layer initialized
Bluetooth: RFCOMM socket layer initialized
Bluetooth: RFCOMM ver 1.11
Device setup complete
root@cm-debian:~#

Run HCI device configuration utility to retrieve detailed information about the Bluetooth device:

root@cm-debian:~# hciconfig -a     
hci0:	Type: BR/EDR  Bus: UART
	BD Address: 1C:45:93:3E:5D:86  ACL MTU: 1021:4  SCO MTU: 180:4
	UP RUNNING PSCAN 
	RX bytes:6085 acl:38 sco:0 events:279 errors:0
	TX bytes:118688 acl:164 sco:0 commands:78 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 PARK 
	Link mode: SLAVE ACCEPT 
	Name: 'cm-debian-0'
	Class: 0x080100
	Service Classes: Capturing
	Device Class: Computer, Uncategorized
	HCI Version: 4.0 (0x6)  Revision: 0x0
	LMP Version: 4.0 (0x6)  Subversion: 0x1f29
	Manufacturer: Texas Instruments Inc. (13)
root@cm-debian:~#

A2DP Headphones

Scan for available devices to find out Headphones BT device address:

root@cm-debian:~# hcitool scan
Scanning ...
	00:07:A4:F2:B3:CB	Motorola HT820
root@cm-debian:~#

Add new PCM device by editing /etc/asound.conf:

pcm.btheadphones {
   type plug
   slave {
       pcm {
           type bluetooth
           device 00:07:A4:F2:B3:CB
           profile "auto"
       }
   }
   hint {
       show on
       description "BT Headphones"
   }
}
ctl.btheadphones {
  type bluetooth
}

List device names to ensure correct settings in /etc/asound.conf:

root@cm-debian:~# aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
btheadphones
    BT Headphones
default:CARD=cmt3517
    cm-t3517,
    Default Audio Device
sysdefault:CARD=cmt3517
    cm-t3517,
    Default Audio Device
root@cm-debian:~#

Put the headphones in the pairing mode and launch bluez-simple-agent application and provide device PIN code on request:

root@cm-debian:~# bluez-simple-agent hci0 00:07:A4:F2:B3:CB
RequestPinCode (/org/bluez/1335/hci0/dev_00_07_A4_F2_B3_CB)
Enter PIN Code: 0000
Release
New device (/org/bluez/1335/hci0/dev_00_07_A4_F2_B3_CB)
root@cm-debian:~#

Launch aplay playback tool:

root@cm-debian:~# aplay -D btheadphones sample_audio.wav
Playing WAVE 'sample_audio.wav' : Signed 16 bit Little Endian, Rate 22050 Hz, Stereo

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. CM-T3517 Linux example root file system contains file transfer utility for devices that use the OBEX protocol. Following examples demonstrate its usage with mobile phone device.

Enable bluetooth on the phone. On CM-T3517, scan for available devices to find out phone's BT address:

root@cm-debian:~# hcitool scan
Scanning ...
	00:15:2A:20:63:94	Nokia 6230i
root@cm-debian:~#

Ensure the phone supports Obex FTP service:

root@cm-debian:~# 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

root@cm-debian:~#

Pair the device - provide PIN code upon request and confirm permission request on the phone:

root@cm-debian:~# bluez-simple-agent hci0 00:15:2A:20:63:94
RequestPinCode (/org/bluez/1285/hci0/dev_00_15_2A_20_63_94)
Enter PIN Code: 1937
Release
New device (/org/bluez/1285/hci0/dev_00_15_2A_20_63_94)

root@cm-debian:~#

You can launch bluez-simple-agent with no parameters. The agent is tracking requests to all bluetooth devices and triggers pin code confirmation when needed.

List phone's root folder:

root@cm-debian:~# 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
root@cm-debian:~#

Transfer a file from CM-T3517 to the phone:

root@cm-debian:~# 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
root@cm-debian:~#

Retrieve a file from the phone to CM-T3517:

root@cm-debian:~# 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
root@cm-debian:~#

Display options

CM-T3517 evaluation platform has four video output interfaces: LCD, DVI, LVDS and TV-out. Default configuration of Debian Linux for CM-T3517 uses LCD as primary video output. It is possible to switch between the DVI and LCD interfaces on the fly. TV-out can be used simultaneously with LCD or DVI interface.
Linux implementation of the OMAP3 display subsystem is described in detail in Documentation/arm/OMAP/DSS file in the Linux kernel source tree.

Display resolutions

The Toppoly LCD supplied with CM-T3517 evaluation kit supports 480x640 resolution with 18 bits per color
DVI output can be configured for standard resolutions using kernel command line parameter omapfb.mode:
1024x768 - omapfb.mode=dvi:1024x768-24@60

800x600 - omapfb.mode=dvi:800x600-24@60

640x480 - omapfb.mode=dvi:640x480-24@60
TV-out supports PAL and NTSC standards

Examples

Switch from LCD to DVI

echo 0 > /sys/devices/platform/omapdss/display0/enabled
echo "dvi" > /sys/devices/platform/omapdss/manager0/display
fbset -fb /dev/fb0 -xres 1024 -yres 768
echo 1 > /sys/devices/platform/omapdss/display1/enabled

Switch from DVI to LCD

echo 0 > /sys/devices/platform/omapdss/display1/enabled
echo "lcd" > /sys/devices/platform/omapdss/manager0/display
fbset -fb /dev/fb0 -xres 480 -yres 640
echo 1 > /sys/devices/platform/omapdss/display0/enabled

GPIO access

Linux provides simple and convenient GPIO access via sysfs interface. A GPIO should be exported using /sys/class/gpio/export. After the GPIO is exported it is possible to change its direction and value using /sys/class/gpio/gpioX/direction and /sys/class/gpio/gpioX/value attributes.

Example

The following example demonstrates how to configure GPIO 140 as output and set value to high:

echo 140 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio140/direction
echo 1 > /sys/class/gpio/gpio140/value

The above example assums that the corresponding pin is set to mux mode 4 and the GPIO 140 is not requested in the Linux kernel.

Graphics SDK

The CM-T3517 Linux package contains pre-built and ready to run SGX functionality demo programs.

The SGX configuration script must be run on CM-T3730 before first use:

root@cm-debian:~# /etc/init.d/omap-demo

The SGX kernel modules must be loaded prior running the demos:

root@cm-debian:~# /etc/init.d/rc.pvr start

Running Graphics SDK OpenGL ES1.x Demos

To run OpenGL ES1.x demos, perform the following:

root@cm-debian:~# cd /opt/gfxsdkdemos/ogles
root@cm-debian:/opt/gfxsdkdemos/ogles# ./OGLESEvilSkull

This will execute the OGLESEvilSkull demo. Press ‘q’ on the CM-T3517 console to stop the demo execution.

Running Graphics SDK OpenGL ES2.0 Demos

To run OpenGL ES2.x demos, perform the following:

root@cm-debian:~# cd /opt/gfxsdkdemos/ogles2
root@cm-debian:/opt/gfxsdkdemos/ogle2s# ./OGLESFilmTV

This will execute the OGLESFilmTV demo. Press ‘q’ on the CM-T3517 console to stop the demo execution.