Getting Started with SABRE Lite (i.MX6)

31 Mar 2014

Here’s how to quickly get up and running with the SABRE LiteSABRE Lite board.

Pre-Built Images

By default, the SD card that comes with the SABRE Lite board just contains a small demo that shows a couple of slides. Therefore, the first thing that you are going to want to do is put a different OS on there. Boundary Devices has a couple of pre-built images that are listed here:

http://boundarydevices.com/imx6-builds/

I’m going to use the Android Jelly Bean release.

After downloading the image, you can write it to an SD card using Win32 Disk Imager. If you need to format the SD card, the SD Formatter should do the trick.

Once the image is written to the SD card, pop it into the SABRE Lite board and the new OS should boot up.

Troubleshooting

My experience wasn't that easy, so here are some tricks that I learned to help figure out what is going on.

Serial Connection

The SABRE Lite development kit comes with a serial connector that can be used to debug any issues that may arise with your board. Start by connecting the serial connector:

to the J17 connector on the SABRE Lite board:

Then connect the Debug serial connection to your PC.

Once the SABRE Lite board is connected to the PC. Fire up putty on your PC.

Switch the “Connection type” to be “Serial” and input a “Speed” of 115200.

When you click open, chances are that you will see a blank screen. Hitting enter should bring up a U-Boot command prompt. The reason that you have to hit enter is that all of the output already went by. By hitting enter, new output will come over and be displayed. So, to see the boot sequence, press the reset button on the SABRE Lite:

This will show you the boot information. Here’s is the first part of the information that you get:

The information that you get can then be used to debug and fix your issue. Here are some of the ones that I ran into.

Upgrading U-Boot

The latest version of Android JellyBean uses the newer 6x_bootscript and my device came with the older 6q_bootscript installed. This can be discovered by looking at the boot information and seeing a message like unable to read “/6q_bootscript”. To fix this, you need to update your version of U-Boot.

First, you need to download the upgrade image from:

http://boundarydevices.com/switching-u-boot-versions-on-i-mx6/

You want the 6q_upgrade-20121112.zip file. This will upgrade you from the 6q_bootscript to the newer 6x_bootscript. The process is pretty easy. Extract those files and then write them onto an SD card. These files can be written by just dragging and dropping them into the SD card. (No need to use Win32 Disk Imager.) You can put the files on either a normal SD card or a micro SD card.

Then pop the SD card into the SABRE Lite and reset the board. Then, in the putty window type:

run upgradeu

Once this is done you should see a message that says:

U-Boot updated successfully

Now that u-boot is upgraded, you should be able to reset the SABRE Lite board and the OS image that is on your SD card should boot up.

Unbricking

Unfortunately, I managed to get myself into a really bad state where the “run upgradeu” returned with an “upgradeu not found” message. Thankfully, there is another way that you can flash a new U-Boot on to your SABRE Lite board.

First, you need to download the sb_loader program which can be found here:

http://boundarydevices.com/windows-users-and-unbricking-an-i-mx-device/

You will also need the old U-Boot image. This can be found here:

http://boundarydevices.com/switching-u-boot-versions-on-i-mx6/

And this time, you want to get the 6x_downgrade-20121109.zip file. So, put that on an SD card and pop it into the SABRE Lite board. (I had to change the file name from u-boot.nopadding to u-boot.imx.)

Also, copy over the u-boot.imx file into the same directory that the sb_loader program is in. (This isn’t strictly necessary, but it makes the command to run the sb_loader program easier.)

Next you need to set up the SABRE Lite to boot in USB mode. To do this, flip the switches near the center of the board to look like this:

Next, connect a micro USB cable to the SABRE Lite board:

And to your PC. After the messages about trying to find a driver for your USB device go away, then open up a Windows command prompt and navigate to the directory that contains the sb_loader executable and u-boot.imx.

Excellent, now connect to your SABRE Lite through the serial connection like we did before. Once everything is set up, run:

sb_loader.exe –f u-boot.imx

And you should see the following output:

Executed plugin successfully.

Succeed to download u-boot.imx to the device.

Run into the image successfully.

Once this happens, the SABRE Lite board will reboot. One of the first options that comes up is to cancel the boot process by pressing any key. You want to cancel the boot process. This happens very quickly, so it might take a couple of tries.

After you cancel, then you can run:

run upgradeu

This will flash the old boot loader on your SD card to the SABRE Lite board. Once this is done, move the switches on the board back into normal mode:

And reset the SABRE Lite. Now it should be back in business using the old boot loader. To upgrade to the newer boot loader, follow the instructions in the previous section. Note: I tried to go to the new boot loader directly, but it didn’t seem to work. I had to go back to the old one and then upgrade.

HDMI to DVI Connection

The SABRE Lite doesn’t seem to like older DVI monitors that use an HDMI to DVI connector, at least, I was never able to get mine to work. I ended up getting a new monitor to fix it. (I was due for one anyway.)

However, if you think you are in this situation, one pretty easy test is to remove any SD cards from the SABRE LiteSABRE Lite board and start it up. You should see a screen with penguin on top like this:

If not, then it could be an HDMI to DVI problem.

Summary

As you probably guessed, I had a pretty difficult time getting my SABRE Lite board up and running. However, that doesn't mean that you have to. Hopefully these helpful hints can save you hours of debugging.