U-boot-2014.10 transplantation 4th days ---- bare metal buzzer program, uboot2014.10 Transplantation

U-boot-2014.10 transplantation 4th days ---- bare metal buzzer program, uboot2014.10 Transplantation

Hardware Platform: tq2440

Development Environment: Ubuntu-3.11

U-boot: 2014.10

This article allows reprint, please indicate the source: http://blog.csdn.net/fulinus

I. BUZZER asm Assembler:

/*********************************************************************** *        File:  beep.S *     Version:  1.0.0 *   Copyright:  2014 (c) fulinux <fulinux@sina.com> * Description:  This ASM code used to turn beep on/off on TQ2440 board ***********************************************************************/#define GPBCON   0x56000010#define GPBDAT   0x56000014#define GPBUP    0x56000018#define DELAY    0X40000000    .text    .align 2    .global _start_start:    /*Set GPB5,GPB6,GPB7,GPB8 as GPIO OUTPUT mode*/    ldr     r0, =GPBCON    ldr     r1, [r0]    bic     r1, r1, #0x03       /*Set GPBCON for GPB0 as 00 */    orr     r1, r1, #0x01       /*Set GPBCON for GPB0 as GPIOOUT, 0x01*/    str     r1, [r0]    /*Set internal pullup resister*/    ldr     r0, =GPBUP    ldr     r1, [r0]    @orr     r1, r1, #0x01     /*Set bit 0, disable pullup resister*/    bic     r1, r1, #0x01      /*Clear bit 0, enable pullup resister*/    str     r1, [r0]loop:    /*Turn off beep*/    ldr     r2, =GPBDAT    ldr     r3, [r2]    orr     r3, r3, #1          /*Set bit 0 as high level*/    str     r3, [r2]    ldr     r0, =DELAY          /*Sleep for a while*/    bl      delay    /*Turn on beep*/    ldr     r3, [r2]    bic     r3, r3, #1          /*Set bit 0 as high level*/    str     r3, [r2]    ldr     r0, =DELAY          /*Sleep for a while*/    bl      delay    b       loop                /*Loop running*/delay:    sub     r0, r0, #1    cmp     r0, #0x0    bne     delay    mov     pc, lr

The program was modified based on the led. S program yesterday. The makefile file is the same as the file of yesterday, but the execution file name is changed:

BINAME = beep

2. ARM Assembly and C Language Combination

Switching from asm to C functions is also an important technical point. We need to do the following in the ARM assembler program:

1. Shut down the watchdog;

2. Block interruptions;

3. Jump to the main function in C code.

1. ARM Assembler

/*********************************************************************** *        File:  start.S *     Version:  1.0.0 *   Copyright:  2011 (c) Guo Wenxue <guowenxue@gmail.com> * Description:  This ASM used to disable watch dog and interrupt, then call C code to  *               turn the buzzer on/off on FL2440 board. *   ChangeLog:  1, Release initial version on "Mon Mar 21 21:09:52 CST 2011" * ***********************************************************************/#define pWTCON    0x53000000  /* Watch dog register address */#define INTMSK    0x4A000008  /* Interupt-Controller base addresses */#define INTSUBMSK 0x4A00001C    .text    .align 2    .global _start_start:    /* Disable watch dog */    ldr r0, =pWTCON  /*Save pwTCON address in r0*/    mov r1, #0x0     /*Set r1=0x0*/    str r1, [r0]     /*Move the data in r1 to the address specify by r0*/    /* mask all IRQs by setting all bits in the INTMR - default */    mov r1, #0xffffffff    ldr r0, =INTMSK    str r1, [r0]    ldr r0, =INTSUBMSK    ldr r1, =0x7fff    /*There are 15 bits used in INTSUBMSK on S3C2440*/    str r1, [r0]    bl mainhalt_loop:    b halt_loop

2. C Language Program

/*********************************************************************** *        File:  beep.c *     Version:  1.0.0 *   Copyright:  2011 (c) Guo Wenxue <guowenxue@gmail.com> * Description:  This C code used to turn buzzer on/off on FL2440 board *   ChangeLog:  1, Release initial version on "Mon Mar 21 21:09:52 CST 2011" * ***********************************************************************/#define GPBCON   (*(unsigned long volatile *)0x56000010)#define GPBDAT   (*(unsigned long volatile *)0x56000014)#define GPBUP    (*(unsigned long volatile *)0x56000018)#define BEEP         0    /*Buzzer us GPB0 */#define DELAY_TIME   40000000static inline void delay (unsigned long loops){    __asm__ volatile ("1:\n"            "subs %0, %1, #1\n"            "bne 1b":"=r" (loops):"0" (loops));}int main(void){    GPBCON = (GPBCON|0x3)&0x1; /* Set GPB0 as GPIO output mode(0x01) */    GPBUP &= ~1;               /* Enable pullup resister */    GPBDAT |= 0x560;    while(1)    {        GPBDAT &= ~(1<<BEEP);  /* Set Beep GPIO as low level */        delay(DELAY_TIME);        GPBDAT |= 1<<BEEP;     /* Set Beep GPIO as high level */        delay(DELAY_TIME);    }}

Obviously, we need to execute the ARM assembler program first, and then jump from the assembler program to the C program. However, the compiler does not know whether to put the C code segment or the ARM assembly code segment first, therefore, we need to inform the compiler how to compile and connect. There is a lds file. The content in this file determines the placement relationship of each code segment in the program. You can see in the makefile file below how to pass the file to the compiler.

3. lds File

/*********************************************************************** *        File:  beep.lds *     Version:  1.0.0 *   Copyright:  2011 (c) Guo Wenxue <guowenxue@gmail.com> * Description:  Cross tool link text, refer to u-boot.lds *   ChangeLog:  1, Release initial version on "Mon Mar 21 21:09:52 CST 2011" ***********************************************************************/                             OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")OUTPUT_ARCH(arm)ENTRY(_start)SECTIONS{    . = 0x33000000;    .text : {        start.o(.text*) /* by fulinux modified */        *(.text*)                            *(.rodata)    }    .data ALIGN(4): {        *(.data)    }    .bss ALIGN(4): {        *(.bss)    }

4. makefile

# ***********************************************************************# *        File:  makefile# *     Version:  1.0.0# *   Copyright:  2011 (c) Guo Wenxue <guowenxue@gmail.com># * Description:  Makefile used to cross compile the ASM and C source code# *   ChangeLog:  1, Release initial version on "Mon Mar 21 21:09:52 CST 2011"# *# ***********************************************************************BINAME = beepTEXTBASE = 0x33000000CROSS = /opt/buildroot-2012.08/arm920t/usr/bin/arm-linux-CC      = $(CROSS)gccLD      = $(CROSS)ldAR      = $(CROSS)arOBJCOPY = $(CROSS)objcopyOBJDUMP = $(CROSS)objdumpSTRIP   = $(CROSS)stripREADELF = $(CROSS)readelfCFLAGS  = -g -O2 -Wall -nostdinc -nostdlib -fno-builtinAFLAGS  = $(CFLAGS) -D__ASSEMBLY__LDSCRIPT = ${BINAME}.ldsLDFLAGS  = -nostartfiles -T $(LDSCRIPT) -Ttext $(TEXTBASE)SRC_C   = $(wildcard *.c)SRC_S   = $(wildcard *.S)OBJ_C   = $(patsubst %.c,%.o,$(SRC_C))OBJ_S   = $(patsubst %.S,%.o,$(SRC_S))OBJ_ALL = $(OBJ_C) $(OBJ_S).PHONY : allall: ${OBJ_ALL}    ${LD} $(LDFLAGS) -o ${BINAME}.elf ${OBJ_ALL}    ${OBJCOPY} -O binary -S ${BINAME}.elf ${BINAME}.bin    rm -f *.elf *.o%.o: %.S            $(CC) $(AFLAGS) -c -o $@ $<%.o: %.c            $(CC) $(CFLAGS) -c -o $@ $<install:    cp ${BINAME}.bin ~/winxp -f --reply=yesclean:    rm -f *.elf *.o    rm -f ${BINAME}.bin

File

LDSCRIPT = ${BINAME}.lds

That is, the beep. lds file.

5. Compile and run

After compilation, the beep. bin program is burned to the SDRAM for execution through J-link:

h  speed 12000  loadbin D:\kupan\temp\beep.bin 0x33000000  setpc 0x33000000  g

You will be able to hear it!

Iii. ARM Assembly of led marquee and C Language Program:

/*********************************************************************** *        File:  led.c *     Version:  1.0.0 *   Copyright:  2011 (c) Guo Wenxue <guowenxue@gmail.com> * Description:  This C code used to turn LED0~LED4 on on FL2440 board *   ChangeLog:  1, Release initial version on "Mon Mar 21 21:09:52 CST 2011" *      Modify:  fulinux@sina.com ***********************************************************************/#define GPBCON   (*(unsigned long volatile *)0x56000010)#define GPBDAT   (*(unsigned long volatile *)0x56000014)#define GPBUP    (*(unsigned long volatile *)0x56000018)#define LED0     5    /*LED0 use GPB5*/#define LED1     6    /*LED1 use GPB6*/#define LED2     7    /*LED2 use GPB7*/#define LED3     8    /*LED3 use GPB8*/#define DELAY_TIME   40000000static inline void delay (unsigned long loops){    __asm__ volatile ("1:\n"        "subs %0, %1, #1\n"        "bne 1b":"=r" (loops):"0" (loops));}void led_init(void){    /*  Set GPB5,GPB6,GPB7,GPB8 as GPIO mode(0x01) */     GPBCON = (GPBCON & ~0x3FC00) | 0x15400;    GPBUP &= ~0x01E0;    /* Set GPB5,GPB6,GPB7,GPB8 as high level, to turn LED0,LED1,LED2,LED3 off */    GPBDAT |= 0x01E0;}void led_off(void){    /* Set GPB5,GPB6,GPB7,GPB8 as high level, to turn LED0,LED1,LED2,LED3 off */    GPBDAT |= 0x01E0;    delay(DELAY_TIME);}void led_on(int led){    /* Turn LED0 on */    GPBDAT &= ~(1<<led);    delay(DELAY_TIME);}int main(void){    led_init();    while(1)    {        led_off();        led_on(LED0);        led_on(LED1);        led_on(LED2);        led_on(LED3);    }}

Other files are similar and slightly modified.