Вот пример инициализации на asm'е для 32-х бит, закомменченные значения, насколько я помню,
для 16...
Код
; ***************************************************************************
; * SDRAM Controller Configuration
; 1. Wait 100us
; 2. Set SDRAM controller device mode register
ldr r0, =0x01210008 ;0x0022000c
ldr r1, =SDRAMDevCfg0
str r0, [r1]
ldr r1, =SDRAMDevCfg1
str r0, [r1]
ldr r1, =SDRAMDevCfg2
str r0, [r1]
ldr r1, =SDRAMDevCfg3
str r0, [r1]
ldr r1, =GlConfig
ldr r2, =RefrshTimr
; 3. Set Initialize, MRS, and CKE bits in the GlConfig register
ldr r0, =0x80000003
str r0, [r1]
; 4. Wait 200us
mov r0, #0x4000
1
subs r0, r0, #0x01
bne %B1
; 5. Clear MRS bit
ldr r0, =0x80000001
str r0, [r1]
; 6. Write 10 into the refresh timer register
mov r0, #0x0a
str r0, [r2]
; 7. Wait at least 80 clock cycles
mov r0, #0x100
1
subs r0, r0, #0x01
bne %B1
; 8. Program the refresh counter
mov r0, #0x320
str r0, [r2]
; 9. Initialize = 0, MRS = 1
ldr r0, =0x80000002
str r0, [r1]
ldr r0, =0xc0008800 ;0xf0006600
ldr r0, [r0]
; 10.
; 11. Clear MRS
ldr r0, =0x80000000
str r0, [r1]