Timesys Getting Started Guide for Compulab SBC-FX6



This document will describe in detail the procedures for booting a Linux kernel image and mounting a root file system from an SD Card on the Compulab SBC-FX6.


Host Requirements

To properly boot the Compulab SBC-FX6 using software from Timesys, your host machine must meet the following requirements:

  • Modern GNU/Linux Distribution. Timesys recommends one of the following distributions:
    • Ubuntu (Most recent release or LTS)
    • Fedora (Most recent release)
  • Root or sudo permission on the Development Host.
  • A copy of the Linux Kernel (uImage-3.0-ts-armv7l) and Root File System (rootfs.tar.gz) for the Target Board downloaded from Factory. These are found in the output directory of your online build, or in the directory build_armv7l-timesys-linux-<libc>/images/ on the command line.
  • An available serial port on your Development Host.
  • A SD card slot or adapter on your Development Host.

Target Requirements

To boot the Compulab SBC-FX6, you will need the following items:

  • Compulab SBC-FX6
  • 12V Power Supply
  • RS232 Serial Cable (DB9 to RJ11)

Once you have all of the necessary components, you should perform the following steps:

  1. Connect the UART port of the SBC-FX6 to the serial port of your workstation using the RS232 serial cable.
  2. Connect the power supply to your board.

Preparing the Target

Configuring Serial Communication

The SBC-FX6 uses a serial debug port to communicate with the host machine. The commands discussed in this section are meant to be performed by a privileged user account. This requires the root login or prepending each command with sudo.

Using Minicom

  1. Start minicom on your host machine in configuration mode. As root:

    # minicom -o -s -w

  2. A menu of configuration should appear. Use the Down-arrow key to scroll down and select the Serial port setup option, and press Enter.
  3. Verify that the listed serial port is the same one that is connected to the target board. If it is not, press A, and enter the correct device. This is /dev/ttyS0 on most Linux distributions.
  4. Set the Bps/Par/Bits option by pressing the letter E and using the next menu to set the appropriate values. You press the key that corresponds to the value 115200, then press Enter.
  5. Set Hardware flow control to No using the F key.
  6. Set Software flow control to No using the G key.
  7. Press Enter to return to the main configuration menu, and then press Esc to exit this menu.
  8. Reset the board, and wait for a moment. If you do not see output from the board, press Enter several times until you see the prompt. If you do not see any output from the board, and have verified that the serial terminal connection is setup correctly, contact your board vendor.

TIP: If you experience an error similar to Device /dev/ttyS0 is locked when starting minicom, it usually means that another process is using the serial port (which is usually another instance of minicom). You can find the process that is currently using the serial port by executing the following:

# fuser /dev/ttyS0
/dev/ttyS0:         28358

# ps 28358
  28923 pts/0    S+    0:00 minicom

This process can also be killed directly with fuser as root. Please use this command with caution:

# fuser -k /dev/ttyS0

Using GNU Screen

To quickly connect to a board using Gnu Screen, execute the following:

# screen /dev/ttyS0 115200

For more information about using screen, please consult the man page, or view the manual online at http://www.gnu.org/software/screen/manual/screen.html

Preparing the Secure Digital Card

The SBC-FX6 boots from an SD card. Some kits may be shipped with one that contains a sample kernel and RFS preloaded. We will be replacing these with the kernel and RFS from Factory. If you are using a blank SD card or have trouble replacing the software on the preloaded one, see Partitioning the SD Card. Otherwise, skip directly to Writing Boot Files to the SD Card.

Before you begin, you should determine the name of your SD card on your host system. To do so:

  1. Connect the SD card to your host system. Many modern systems have SD card slots on the case, or you can purchase a USB SD Card Reader for around $15 US.
  2. Determine the device name of the SD Card. This can be done using dmesg. In the following example, the device is /dev/sdX, which contains one partition sdX1.

    $ dmesg | tail
    [88050.184080] sd 4:0:0:0: [sdX] 1990656 512-byte hardware sectors: (1.01 GB/972 MiB)
    [88050.184821] sd 4:0:0:0: [sdX] Write Protect is off
    [88050.184824] sd 4:0:0:0: [sdX] Mode Sense: 03 00 00 00
    [88050.184827] sd 4:0:0:0: [sdX] Assuming drive cache: write through
    [88050.185575] sd 4:0:0:0: [sdX] 1990656 512-byte hardware sectors: (1.01 GB/972 MiB)
    [88050.186323] sd 4:0:0:0: [sdX] Write Protect is off
    [88050.186325] sd 4:0:0:0: [sdX] Mode Sense: 03 00 00 00
    [88050.186327] sd 4:0:0:0: [sdX] Assuming drive cache: write through
    [88050.186330]  sdX: sdX1

Partitioning the SD card

If you want to use a different SD card or its contents become corrupted, you can use the fdisk tool to create a single Linux partition on your SD card. Please note that all data on the card will be lost upon completion of these steps.
  1. Unmount the partition if it was automounted by using the umount command.
    $ umount /dev/sdX1
  2. As root, run the fdisk utility on the drive.
    $ sudo fdisk /dev/sdX
  3. In fdisk, Delete the existing partition table and create a new one using the o command.
    Command (m for help): o
    Building a new DOS disklabel with disk identifier 0x8b025602.
    Changes will remain in memory only, until you decide to write them.
    After that, of course, the previous content won't be recoverable.
  4. Create a new primary partition using the n command.

    Command (m for help): n
    Partition type:
       p   primary (0 primary, 0 extended, 4 free)
       e   extended
    Select (default p): p
    Partition number (1-4, default 1): 1
    First sector (2048-30679039, default 2048):
    Using default value 2048
    Last sector, +sectors or +sizeK,M,G (2048-30679039, default 30679039):
    Using default value 30679039

  5. Verify that the partition table is correct by using the p command. It should look similar to the following:

    Command (m for help): p                                                         
    Disk /dev/sdX: 15.7 GB, 15707668480 bytes
    64 heads, 32 sectors/track, 14980 cylinders, total 30679040 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x6eaae8f8

       Device Boot      Start         End      Blocks   Id  System
    /dev/sdX1            2048    30679039    14773960   83  Linux

  6. This step will destroy all data on the SD Card - Write the partition table to the card using the w command.

    Command (m for help): w
    The partition table has been altered!

    Calling ioctl() to re-read partition table.

    WARNING: If you have created or modified any DOS 6.x
    partitions, please see the fdisk manual page for additional
    Syncing disks.

  7. Format the first partition of the SD card with the ext4 filesystem using the mkfs.ext4 tool.

    $ sudo /sbin/mkfs.ext4 -L rfs /dev/sdX1

Writing Boot Files to the SD Card

  1. Mount the partition. You can remove and reinsert the card to trigger the automount, or you can use the mount command to mount the partition to an arbitrary location.

    $ sudo mount /dev/sdX1 /media/rfs

  2. Generate the Bootloader image using dd:

    $sudo dd if=/dev/zero count=500 bs=1K | tr '\000' '\377' > cm-fx6-firmware
    $sudo  dd if=SPL  of=cm-fx6-firmware bs=1K seek=1 conv=notrunc && dd if=u-boot.img of=cm-fx6-firmware bs=1K seek=64 conv=notrunc

  3. Write the bootloader image to the card using dd. Note that you are writing to the raw block device, not the partition (e.g. /dev/sdX as opposed to /dev/sdX1).

    $ sudo dd if=cm-fx6-firmware of=/dev/sdX bs=1K skip=1 seek=1 oflag=dsync

  4. As root, extract the rootfs.tar.gz to the EXT4 partition.

    $ sudo tar -xf rootfs.tar.gz -C /media/rfs/

  5. Copy the kernel image into the RFS as a file named uImage.

    $ sudo mkdir /media/rfs/boot
    $ sudo cp uImage-3.0-ts-armv7l /media/rfs/boot/uImage

  6. Unmount the partition:

    $ sync
    $ cd /media/
    $ sudo umount RFS/

Remove the SD Card from your host, and slide it into the slot of your SBC-FX6. You should hear the card 'click' into place.

Preparing the Host

No additional host setup is required to boot from SD.

Booting the Board

Set Environment Variables

You must set a few environment variables in order to boot the board from the SD card. This is done with the setenv and saveenv commands in U-Boot. On the target, set the following environment variables:

Variable Value
bootargs console=ttymxc3,115200 root=/dev/mmcblk0p1 rootwait
bootcmd mmc dev 1\; ext2load mmc 1:1 0x10800000 boot/uImage\; bootm 0x10800000


> setenv bootargs console=ttymxc3,115200 root=/dev/mmcblk0p1 rootwait
> setenv bootcmd mmc dev 1\; ext2load mmc 1:1 0x10800000 boot/uImage\; bootm 0x10800000
> saveenv

Load The Kernel

You can use the mmc subsystem to load the kernel from the SD card.


> mmc dev 1
> ext2load mmc 1:1 0x10800000 boot/uImage
reading boot/uImage

3008612 bytes read

Boot the Kernel

The bootm command is used to boot the kernel. It loads the file that was previously loaded using the fatload command.


> bootm 0x10800000
## Booting kernel from Legacy Image at 0x10800000 ..
   Image Name:   Linux-3.0
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    3008548 Bytes =  2.9 MB
   Load Address: 80008000
   Entry Point:  80008000
   Verifying Checksum ... OK
   Loading Kernel Image ... OK

Additional Information

The SBC-FX6 supports multiple display configurations. The displays are enabled on the kernel command line at boot time. Configure each display with a video variable and a mxcfbx argument in your bootargs, replacing x is a 0 (primary) or 1 (secondary) to correspond to which display you wish to be primary:
  • HDMI: video=mxcfb0:dev=hdmi,1920x1080M-32@50,if=RGB32
  • LVDS: video=mxcfb0:dev=ldb,1366x768M-18@60,if=RGB666
  • DVI: video=mxcfb0:dev=dvi,1280x800M-32@50,if=RGB32

Multiple Displays

The board can support two display connections at a time. This is accomplished by providing a video variable for both mxcfb0 and mxcfb1 on the kernel command line. Typically, graphical applications will use the device marked as 'mxcfb0' as the primary display.


HDMI (primary display), and LVDS Panel (secondary display)

video=mxcfb0:dev=hdmi,1920x1080M-32@50,if=RGB32 video=mxcfb2:dev=ldb,1366x768M-18@60,if=RGB666

Factory Documentation