I have a pilot series of custom boards with imx287, 64MB DDR2, power + boot _prep, non OS.
I tested configurations from Table14 in datasheet - recommended operating states.
These are first test results:
1) core 454MHz DDR2 205MHz - RAM R/W errors sometimes, on some units (max. config)
2) core 454MHz DDR2 160MHz - RAM R/W errors sometimes, on some units (this is not listed in datasheet as recommended state)
3) core 393MHz DDR2 160MHz - everything ok an all units, acceptable for our application.
Tested few voltages, including max. levels, don't really change results.
What I don't know is where is the problem - core speed, DDR2 speed or relationship between them?
I understand this could be poor layout of DDR2, cause we're using simple EDA PCB software.
I also know that DDR2 configuration might need some changes in software - a fine tuning of timings, but I don't want to do it now.
But if above is true, than test 2) and test 3) should work the same, right?
Core 454MHz without external RAM R/W (runs from internal RAM - boot_prep) run stable on all units, so it seems it's not an issue.