ARM9 2440 按键与LED 小实验

;time 2012-12-24

;developer:MDK 4.0 and J-link v8

;developer board MINI 2440

;function: LEDs and beeper on when pressing key

;GOOD: simple

;BAD: low efficiency

;--------------------------------------------------

;macro the register 

pGPBCON   EQU 0x56000010

pGPBDAT   EQU 0x56000014

pGPBUP    EQU 0x56000018

pGPGCON   EQU 0x56000060

pGPGDAT   EQU 0x56000064

pGPGUP    EQU 0x56000068

AREA led_key, CODE, READONLY ;define code section and its property

ENTRY ;declare this entrance of the program

NOP

;set the GPB pins with output funtion

LDR r0,= pGPBCON

LDR r1,[r0]

MOV r2,#(0x55<<10)

ORR r1,r1,r2

ADD r1,#0x1

STR r1,[r0]

;disable the poll-up

LDR r0,= pGPBUP

LDR r1,[r0]

LDR r2,=0x7ff

ORR r1,r1,r2

STR r1,[r0]

;init the output pins at the high voltage level

  LDR r0,= pGPBDAT

LDR r1,[r0]

LDR r2,=0x7fe

ORR r1,r1,r2

STR r1,[r0]

NOP

NOP

;set the GPG pins with input funtion 

LDR r0,= pGPGCON

MOV r1,#0x0

STR r1,[r0]

;disable the poll-up

  LDR r0,= pGPGUP

LDR r1,[r0]

LDR r2,=0xffff

ORR r1,r1,r2

STR r1,[r0]

;keep the original val of  pGPGDAT for comparing

LDR r0,= pGPGDAT

LDR r3,[r0]

;set looping method to check the status of inputs from key

LOOP

LDR r0,= pGPGDAT

LDR r1,[r0]

CMP r1,r3

BEQ LOOP ;no press on the keys

BNE LED_DISPLAY ;press on the keys

LED_DISPLAY

LDR r0,= pGPBDAT

LDR r1,=0x1

STR r1,[r0] ; display leds and enable beeper

BL DELAY

LDR r0,= pGPBDAT

LDR r1,=0x7fe

STR r1,[r0] ;close leds and beeper

B LOOP

DELAY

LDR r0,=0xfff

TMP

SUB r0,r0,#0x1

CMP r0,#0x0

BNE TMP

MOV pc,lr

END