/***********************************************************************
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* File: start.S
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* Version: 1.0.0
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* Copyright: 2011 (c) Guo Wenxue <guowenxue@gmail.com>
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* Description: This ASM used to detect the four keys status, if it's pressed down
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* then call the C function to turn the buzzer beep and LED on
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* ChangeLog: 1, Release initial version on "Tue Mar 22 21:58:24 CST 2011"
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*
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***********************************************************************/
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#define pWTCON 0x53000000 /* Watch dog register address */
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#define INTMSK 0x4A000008 /* Interupt-Controller base addresses */
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#define INTSUBMSK 0x4A00001C
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#define GPFCON 0x56000050
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#define GPFDAT 0x56000054
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#define GPFUP 0x56000058
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#define KEY2 0 /*KEY S2 use GPF0/EINT0 port*/
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#define KEY3 2 /*KEY S3 use GPF2/EINT2 port*/
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#define KEY4 3 /*KEY S4 use GPF3/EINT3 port*/
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#define KEY5 4 /*KEY S5 use GPF4/EINT4 port*/
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.text
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.align 2
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.global _start
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_start:
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/* Disable watch dog */
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ldr r0, =pWTCON /*Save pwTCON address in r0*/
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mov r1, #0x0 /*Set r1=0x0*/
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str r1, [r0] /*Move the data in r1 to the address specify by r0*/
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/* mask all IRQs by setting all bits in the INTMR - default */
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mov r1, #0xffffffff
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ldr r0, =INTMSK
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str r1, [r0]
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ldr r0, =INTSUBMSK
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ldr r1, =0x7fff /*There are 15 bits used in INTSUBMSK on S3C2440*/
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str r1, [r0]
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/*Set Beep GPIO port as GPIO input mode*/
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ldr r0, =GPFCON
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ldr r1, [r0]
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bic r1, r1, #0xf3 /* Set GPF0, GPF2, GPF3, as GPIO input mode(00)*/
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bic r1, r1, #0x0300 /* Set GPF4 as GPIO input mode(00)*/
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str r1, [r0]
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bl init_led_buzzer /*Call C function to init buzzer and LED GPIO port*/
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loop_detect:
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bl turn_led_buzzer_off
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ldr r1, =GPFDAT /*Read the four key GPIO data port*/
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ldr r2, [r1]
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/*Check Key2 pressed down or not*/
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mov r0, #0 /*Turn LED0 on*/
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tst r2, #0x1
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bleq led_beep_on
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/*Check Key3 pressed down or not*/
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mov r0, #1 /*Turn LED1 on*/
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tst r2, #0x4
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bleq led_beep_on
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/*Check Key4 pressed down or not*/
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mov r0, #2 /*Turn LED2 on*/
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tst r2, #0x8
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bleq led_beep_on
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/*Check Key5 pressed down or not*/
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mov r0, #3 /*Turn LED3 on*/
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tst r2, #0x10
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bleq led_beep_on
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/*No key pressed, detect again*/
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b loop_detect
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led_beep_on:
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bl turn_led_buzzer_on /*Turn buzzer beep*/
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@mov pc, lr /*Why mov lr, pc can not work?*/
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b loop_detect
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/*Won't come here*/
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halt_loop:
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b halt_loop
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