eMMC Flash Storage and microSD Card Boot on BeagleBone

Trent,

When I read the beaglebone black documentation, it was my understanding that the boot button had to be pressed every time you wanted to use the SD card to be the boot device.  That has not been my experience though.  I have been booting from the SD card because it has the latest operating system.  (I haven't bothered burning it to the eMMC chip).  I had to press the boot button the first time I wanted to use the SD card.  After that, it always booted from the SD card, without me pressing the boot button.  It seems like it's a latching button.

I was thinking I should try removing the SD card, and seeing if that stopped the latching.  But it's on my long list of mysteries to solve.

Allen

Hi Allen,

It seems like the eMMC boots without the sd to an outdated iot image that was previously installed. I origally flashed the eMMC on both my Black Wireless and Blue with the beagleboard debian iot image. When booting from the microSD, I've always held the sd boot button. I didn't know if it was possible to boot from sd without holding the button down.

Trent

In case anyone really wanted to know the answer, I ran some tests today.  Yes, the Boot button (which lets you boot from the SD card instead of the on-board eMMC memory) is "latching".  (All this was done with $sudo shutdown now) More latching that I expected:

-boot with no SD card                                                   -boots from eMMC (of course)

-SD card, hold Boot button briefly while power it up     -boots from SD card

-power down, then up,don't hold Boot button               -boots from SD card  (so it's latching)

Then I immediately tried this:

-then remove SD card, power on                      -boots from eMMC (of course)

-power down, then up, don't hold Boot button  -still latched from previous, boots from SD card

much to my surprise, it latches even after having a reboot with the SD card removed.

As an aside, all this rebooting showed me that the eMMC  memory is much faster than the SD card access.  I'm using the clever USB/ethernet connection to 192.168.7.2, and Cloud9 IDE and other apache pages display much faster when using the eMMC.

Hi Allen,

Thank you for for testing this. The boot procedure was a bit confusing at first but you have clarified how the BeagleBone is handling the the microSD.

So I've made the error of holding the boot button every time I wanted to run the image from the microSD.

I wouldn't call it an error.  What you were doing is how I understood the BBB instructions.  Maybe I'll read thru the SRM again to see the exact wording.

Hi Allen,

1. Please let me the which image did you flashed and did you flashed using external power source?2. If now Beaglebone black is flashed using SD card and as you say it boots everytime you power it on with SD card inserted, can use use the SD card for storage? If yes then please let me know how.

3. Can you provide the documentation or its link you reffered?

4. If you know how to execute a specific custom program eg. Pattern of LED lights on GPIO once Beaglebone boots, just like Arduino. How can we do that?

Thanks

Hmmm, good questions.  I should document my testing more thoroughly.

For which image, I used the newest image from beagleboard:

     BeagleBoard.org - latest-images

     At this time the latest is named    Debian 9.5 2018-10-07 4GB SD LXQT 

I did not use the external power source, I connected the BBB using a USB cable to my Linux laptop, and used the included Cloud9 interface to communicate with the BBB (web browser at 192.168.7.2:3000)

I did use a 16 GB SD card with the 4 GB image from beagleboard.org.  I expanded the image so I could use the full 16 GB, so yes, that gives me more storage.  But is your question about using the SD card as external storage instead of a boot device?  If yes, then I would answer that I'd put a USB flash drive into the BBB USB port for that purpose.

For automatically executing a script to illuminate a pattern of LEDs, one answer for the BBB is to use the node.js feature built into the cloud9 IDE.  There is an autorun folder, and when you copy a node program into there, it will run at boot up.  Wire the LEDs to the plentiful GPIO on the beaglebone, test your node.js program, and copy it there when ready.

Do you know what revision OS these boards (BBB) ship with?  I've tried asking the sales people from where I purchased mine and they said that was too technical of a question for them!  Thanks in advance.

The BBB that I have bought new were setting on the shelf for a while.  They were all Rev C, but that rev has been out for a long time.  There's no way to tell until you boot it up.

$ cat /etc/debian_version

from the command line

or with the BBB

$ cat /etc/dogtag

I've flashed mine all to 2018 debian 9, "Stretch", but IIRC, they came with "Jessie" debian 8 OS (so, not Angstrom).  Nothing wrong with Jessie, it works well, but it doesn't have the latest bug fixes.

I've been trying to get the one I have working with LabView.  So, at first I updated everything, only to find out the LINX software that connects with LabView doesn't work.  Then I back-rev'd to 8.6, saw that it worked, and tried incrementally upgrading until it broke again.  Now, it only works after being booted from a fresh 8.6 image write to the SD card and LINX software install.  No other changes, just rebooting (from the card) and it's again broken.  Frustrating is putting it mildly.