NXP Semiconductors MPC5566, Reference Manual

Page: 608 / 1268

SRAM
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 14-5
14.7.1 Example Code
To initialize SRAM correctly, use the store multiple word ( stmw) instruction to implement 64-bit writes
to all SRAM locations. The stmw instruction concatenates two 32-bit registers to implement a single
64-bit write.
The following example code illustrates the use of the stmw instruction to initialize the SRAM ECC bits.
init_RAM:
lis r11,0x4000 # base address of the SRAM, 64-bit word aligned
ori r11,r11,0 # not needed for this address but can be for others
li r12,1024 # loop counter to get all of SRAM;
# 128k/4 bytes/32 GPRs = 1024
mtctr r12
init_ram_loop:
stmw r0,0(r11) # write all 32 GPRs to SRAM
addi r11,r11,128 # inc the ram ptr; 32 GPRs * 4 bytes = 128
bdnz init_ram_loop # loop for 128k of SRAM
blr # done