C means boot  ROM icrocode isn't finding what's expected. Could be your 
hardware or that your needing something in EMC.
You should read the AM335x TRM boot sequence and understand it well  even if 
your only a hardware designer.


- The AM335x has a boot loader (the '0th' stage if you will) physically encoded 
in discrete logic on the chip itself (which is one of the reasons there are v 
1.0, 2.0, 2.1 'silicon'). As such there's no source/compilation/flashing option 
here - you get what you're given!

2 - This boot loader will go through a list of devices it can boot from, 
depending on some of the pins (on the BBB these are hardwired, with a second 
boot option available by long-pressing the 'Boot' button on the board)

3 - In the case of NAND (which again specifically on the BBB is the 2GB eMCC 
directly soldered on the board), the on-chip boot loader will look at the first 
bytes (at this point it knows nothing about 'partitions'), to determine a) the 
start address on the NAND of the MLO/SPL, b) how big the MLO img is, and c) 
where in memory the MLO should be copied.




Surely if you understand hardware you hooked up a logic analyzer to validate 
your assumptions about SD card are valid? and cross checked the boot sequence 
with your pin settings.




It's always a good idea to research what's supposed to happen from the 
technical  documentation  as opposed to asking opinions in group's or making 
assumptions that might be incorrect 

For example the steps above were found using Google they might not be correct 
but I do know a C on console is defined as failure. Obviously your new hardware 
might be an issue.

Have you validated your hardware? Or are you planning to hand this to a 
software engineer and let him figure it out. 

Cold solder joints,  board layout errors , manufacturing problems.  Do you own 
a JTAG or are you expecting to copy a design and ignore all possible electrical 
issues that's a hardware engineer's domain. 

Typically a software board bring up engineer works with the hardware designer 
but as a highly skilled  properly trained electrical engineer its not uncommon 
for you to wear both hats.

Myself being an electrical engineer who does low level firmware I'm quick to 
make sure the hardware is working properly first.

If this is your first design you might want to share that information  and more 
details  of what you have tried otherwise your chances of getting anything 
useful are diminished 
































Sent from Yahoo Mail on Android 
 
  On Thu, May 13, 2021 at 8:32 PM, ASH KR<ashno...@gmail.com> wrote:   In 
addition....

I also checked the uart terminal log, its only printing char 'C' on terminal.

On Friday, May 14, 2021 at 9:37:53 AM UTC+9 ASH KR wrote:

Hi, I need some help in booting my board from SD card.
Since I designed my board (call it BBEv1) based on BBE (beaglebone enhanced) 
and even after I tested it with the same image I was running on BBE/BBB actual 
board through SD. BBEv1 is not getting boot up from SD. Since everything is 
same and exactly as per BBE, I didn't understand the cause of happening so. 
Since there is no ROM code eMMC, it should be by default boot from SD, but 
nothing happen. Is this could be the hardware issue or boot image issue? 
Please suggest.
Thanks,/Ash


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