We have a high percentage of systems in our production that are sporadically locking up during operation. Each system has a MK70FX512 with DDR2 RAM communicating to an TFT-LCD screen with resistive touch capability. Some systems are utilizing the Micron MT47H64M16:H/:M -25 or -25E DDR2 RAM chip and others are using the Alliance AS4C64M16D2A-25BCN component. We are using MQX 4.0, CodeWarrior 10.6.4, Freescale eGUI/D4D 2.30, and a PEmicro MultiLink Universal debug probe.
We are seeing various lockup symptoms from the devices that fail. Some produce hard faults almost immediately after power up. Some lockup and become unresponsive to touch or serial data and have LCD Screens that turn to a greenish hue, and others receive core lockup resets. One of the units that has the LCD screen turn to a greenish hue quite often has gone through some additional testing and it has also been found that the lower 8 bits of 16 bit accesses to the DDR memory always return 00 when this occurs. Note, that lockup can occur after 2 and upto 12 minutes after power on.
We have monitored the task stacks and interrupt stack and neither exceed 40% of their allotted space. When the system Locks up nothing is ever reported. We occasionally will get a BUS Fault that is reported. We are unsure as to the cause of this too, but repowering the unit fixes this issue.
We suspect a possible issue with the DDR2 Ram because we keep the LCD Frame buffer in this area.
We have used the K70Memctrl program to create the ddr_setup routine.
Fixes have been applied to the DDR_CR values so that the values are now correct and/or in the correct location, as per K70P256M150SF3RM (Reference Manual) Rev. 4, 10/2015.
Corrected tCPD in DDR_CR10 (value was missing)
Corrected tREF in DDR_CR12 (value was smaller than entered)
Moved p2typ to DDR_CR44, moved qfull/fstwr/wrlatr to DDR_CR29.
Any thoughts on this situation would be greatly appreciated.
