AnsweredAssumed Answered

Memory management in the MPC5200B

Question asked by foamfollower on Mar 14, 2013
Latest reply on May 5, 2016 by Pavel Chubakov


I am new at programming the MPC5200b and I was hoping someone could answer some questions about configuring the SDRAM controller and the LocalPlus Bus.


At time of power applied to the MPC5200b, the configuration pins are set to have the processor start in the Low Boot space.  The documentation states that the boot space has a total of 512Kbytes.  Does this mean that the following registers will be initialized as shown below?

MBAR+0x004C  = 0x0000_0000

MBAR+0x0050  = 0x0000_0007


MBAR+0x004C  = 0x0000_0000

MBAR+0x0050  = 0x0000_FFFF


During the course of configuring the MPC5200B during Boot, should I change the lower Boot Space Address to

MBAR+0x004C = 0x0000_FC00  does the program pointer automatically change to this start address + current location or do I need to make a jump to this location on the next instruction?  I am wondering how the program pointer handles the change in the start address for the boot chip select.


My last question deals with the initialization of the SDRAM chip select.  The documentation states that the register request the XLB starting address along with the size of memory.  Does the XLB starting address have the same definitions as that used by the localplus bus?  For example, if I program the SDRAM register with a start XLB address of 0x0000_0000 does this correlate to the localplus bus boot_CS start address of 0x0000_0000?  Do I need to change the boot_CS start address before I set the SDRAM XLB address to 0x0000_0000 or does the G2_LE core distinguiish the difference between the localplus bus and the SDRAM controller?


Thanks for your help