NUC972 >> Assembly
Phase Locked Loop(PLL)
參考資訊：
1. pdf
2. NUC970_NonOS_BSP
DIVCTL0
APLL、UPLL
PLL
main.s
.equ GPIOB_DIR, (0xb8003000 + 0x40) .equ GPIOB_DATAOUT, (0xb8003000 + 0x44) .equ CLK_PCLKEN0, (0xb0000200 + 0x18) .equ CLK_DIVCTL0, (0xb0000200 + 0x20) .equ CLK_APLLCON, (0xb0000200 + 0x60) .equ CLK_UPLLCON, (0xb0000200 + 0x64) .text .align 2 .global _start _start: b reset _undef: b . _swi: b . _pabort: b . _dabort: b . _reserved: b . _irq: b . _fiq: b . reset: ldr r0, =CLK_UPLLCON ldr r1, =0x4000001b str r1, [r0] ldr r0, =CLK_DIVCTL0 ldr r1, [r0] and r1, #0xfff0ffff str r1, [r0] ldr r0, =CLK_PCLKEN0 ldr r1, [r0] orr r1, #(1 << 3) str r1, [r0] ldr r0, =GPIOB_DIR ldr r1, =(1 << 0) str r1, [r0] loop: ldr r0, =GPIOB_DATAOUT ldr r1, =(1 << 0) str r1, [r0] ldr r4, =1000000 1: nop subs r4, r4, #1 bne 1b ldr r0, =GPIOB_DATAOUT ldr r1, =~(1 << 0) str r1, [r0] ldr r4, =1000000 1: nop subs r4, r4, #1 bne 1b b loop .end
P.S. 除了詭異的SYS_PWRON、APLL、UPLL，還需要注意PA.2(1 = System clock is from UPLL output)腳位的設定，司徒目前PA.2是懸空，建議接到VCC，正確使用UPLL
完成
