Andras Lipoth

DDR troubleshooting tips?

Discussion created by Andras Lipoth on Jun 6, 2013

I am trying bring up a LPDDR chip on our board (using K70) and ran into problems. After power up I see a pattern repeated every four bytes. When I write a byte and read back a block of memory I either don't see any effect or see the test byte repeated on every fourth byte, see attached hexdump. Does this behaviour make any sense? Does it hint at something fundamental?


I don't have access to the control or data lines of the memory chip (BGA package), all I can scope is the clock, which seems to be within specs. The chip does have power and  the cache is disabled. The DDR init script is created by Freescale's K70Memctrl.exe tool,  using a memory configuration based on the memory's datasheet.


How do I go about troubleshooting this issue? Is there any way to further diagnose the problem without access to the control/data lines? I couldn't find any debugging facility in the memory controller.


We might be able to respin our board with test points (avoided them due to space constraints) - what test points should we have? Will the control lines suffice or must have data and/or address lines as well?

Original Attachment has been moved to: