sdram init MRS command

陈希 xchen at sunrisetelecom.com.cn
Fri Dec 22 20:34:18 EST 2006


Hi,

	CPU type: MPC885
	SDRAM:    48LC16M16A2-75 x2

 	memctl->memc_mar=	0x00000088;
	memctl->memc_or1 = CFG_OR1_PRELIM;
	memctl->memc_br1 = CFG_BR1_PRELIM;
	memctl->memc_mamr = CFG_MAMR_9COL & (~(MAMR_PTAE));	/* no
refresh yet */
	udelay(200);
	memctl->memc_mcr=0x80002105; 	->>>>>>>>  after this I think the
function should sent data through address line
	udelay(1);
	memctl->memc_mamr= ( (CFG_MAMR_9COL &0xfffffff0) |0x08);
	udelay(200);

	As you see, The code set mar and run the ram word 0x05-0x07 to
precharge ,nop and MRS. After run MRS command I think the code should write
data through address line to set mode. But I don't find this step.  The
datasheet said mode redister are set  through A0-A12. My question is how the
mpc8xx set sdram mode.

Thanks
Andy




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