[quote user="mirco gomiero"]
Occasionally on a programmed NAND Powered Sitara we have seven "CCCCCCC" and Stopped.
None CLOCK to RAM None activity.
[/quote]
"CCCC" printout means MLO is running expecting UART activity. If it stopped then most likely the problem is around power or reset.
[quote user="mirco gomiero"]
2)Why using SYSBOOT[4:0] = 10010b (this configuration solves this occasional ROM blocks) with a not programmed Nand, Sitara do not seek all the Boot Sequence (1st 2nd 3rd 4th) for serching a good boot device?
I thought that if not find a valid NAND it could start from UART with the classic "CCCCCC", but is not so.
[/quote]
Yes it is so. If NAND is not programmed, and the boot mode is "NAND->..->UART0" then NAND boot is skipped and MLO proceeds to the next option up to UART0. I verified that many times.
Another question - what your processor gets from the invalid NAND, or maybe it finds another boot source from the middle of the list. It is not processor's responsibility to find the boot source, it is your responsibility to arrange boot sources so that processor will find the good one.
Also if accounting for the first problem (above) - anything might happen.
If UART0 boot "CCCC" sequence hangs, something wrong is about hardware.
What could be suggested:
1) verify power, reset, floating bootmode pins, ensure no GPIO pins are shorted to VCC or ground.
2) use JTAG debug to see if you can read registers/memory, and step the program in.