1. Mx6u-alpha development board (key input experiment)

One 、 Hardware schematic analysis

Key KEY0 Linked to UART1_CTS On the pin . By default UART1_CTS For the high , When pressed KEY0 in the future UART1_CTS For low .

Two 、 The experimental program was written

​ 1、 Set up UART1_CTS Reuse as GPIO1_IO18
​ 2、 Set up UART1_CTS Electrical properties of .
​ 3、 To configure GPIO1_IO08 Is the input mode .
​ 4、 Read the key value , That is to say GPIO1_IO08 High and low levels of

// bsp_gpio.h
#ifndef _BSP_GPIO_H
#define _BSP_GPIO_H
#define _BSP_KEY_H
#include "imx6ul.h"
/*  Enumeration type and structure definition  */
typedef enum _gpio_pin_direction
{
    
    kGPIO_DigitalInput = 0U,  		/*  Input  */
    kGPIO_DigitalOutput = 1U, 		/*  Output  */
} gpio_pin_direction_t;
	

typedef struct _gpio_pin_config
{
    
    gpio_pin_direction_t direction; /* GPIO Direction : Input or output  */
    uint8_t outputLogic;            /*  If it's output , Default output level  */
} gpio_pin_config_t;


/*  Function declaration  */
void gpio_init(GPIO_Type *base, int pin, gpio_pin_config_t *config);
int gpio_pinread(GPIO_Type *base, int pin);
void gpio_pinwrite(GPIO_Type *base, int pin, int value);

#endif

//bsp_gpio.h
#include "bsp_gpio.h"
void gpio_init(GPIO_Type *base, int pin, gpio_pin_config_t *config)
{
    
	if(config->direction == kGPIO_DigitalInput) /*  Input  */
	{
    
		base->GDIR &= ~( 1 << pin);
	}
	else										/*  Output  */
	{
    
		base->GDIR |= 1 << pin;
		gpio_pinwrite(base,pin, config->outputLogic);/*  Set the default output level  */
	}
}

 int gpio_pinread(GPIO_Type *base, int pin)
 {
    
	 return (((base->DR) >> pin) & 0x1);
 }
void gpio_pinwrite(GPIO_Type *base, int pin, int value)
{
    
	 if (value == 0U)
	 {
    
		 base->DR &= ~(1U << pin); /*  Output low level  */
	 }
	 else
	 {
    
		 base->DR |= (1U << pin); /*  Output high level  */
	 }
}

//bsp_key.h
#ifndef _BSP_KEY_H
#define _BSP_KEY_H
#include "imx6ul.h"

/*  Define key values  */
enum keyvalue{
    
	KEY_NONE   = 0,
	KEY0_VALUE,
	KEY1_VALUE,
	KEY2_VALUE,
};

/*  Function declaration  */
void key_init(void);
int key_getvalue(void);


#endif

//bsp_key.c
#include "bsp_key.h"
#include "bsp_gpio.h"
#include "bsp_delay.h"

void key_init(void)
{
    	
	gpio_pin_config_t key_config;
	
	// initialization IO Reuse ,  Reuse as GPIO1_IO18
	IOMUXC_SetPinMux(IOMUXC_UART1_CTS_B_GPIO1_IO18,0);

	// To configure UART1_CTS_B Of IO attribute  
	IOMUXC_SetPinConfig(IOMUXC_UART1_CTS_B_GPIO1_IO18,0xF080);
	
	// initialization GPIO
	//GPIO1->GDIR &= ~(1 << 18); /* GPIO1_IO18 Set to input  */ 
	key_config.direction = kGPIO_DigitalInput;
	gpio_init(GPIO1,18, &key_config);
	
}

int key_getvalue(void)
{
    
	int ret = 0;
	static unsigned char release = 1; /*  Release the button  */ 

	if((release==1)&&(gpio_pinread(GPIO1, 18) == 0)) 		/* KEY0 */
	{
    	
		delay(10);		/*  Delay chattering  */
		release = 0;	/*  Mark key press  */
		if(gpio_pinread(GPIO1, 18) == 0)
			ret = KEY0_VALUE;
	}
	else if(gpio_pinread(GPIO1, 18) == 1)
	{
    
		ret = 0;
		release = 1; 	/*  Mark key release  */
	}
	return ret;	
}

//main.c
#include "bsp_clk.h"
#include "bsp_delay.h"
#include "bsp_led.h"
#include "bsp_beep.h"
#include "bsp_key.h"

int main(void)
{
    
	int i = 0;
	int keyvalue = 0;
	unsigned char led_state = OFF;
	unsigned char beep_state = OFF;
	
	clk_enable();		/*  Enable all clocks  */
	led_init();			/*  initialization led */
	beep_init();		/*  initialization beep */
	key_init();			/*  initialization key */
	while(1)			
	{
    	
		keyvalue = key_getvalue();
		if(keyvalue)
		{
    
			switch ((keyvalue))
			{
    
				case KEY0_VALUE:
					beep_state = !beep_state;
					beep_switch(beep_state);
					break;
			}
		}

		i++;
		if(i==50)
		{
    
			i = 0;
			led_state = !led_state;
			led_switch(LED0, led_state);
		}
		delay(10);
	}
	return 0;
}

CROSS_COMPILE 	?= arm-linux-gnueabihf-
TARGET		  	?= key

CC 				:= $(CROSS_COMPILE)gcc
LD				:= $(CROSS_COMPILE)ld
OBJCOPY 		:= $(CROSS_COMPILE)objcopy
OBJDUMP 		:= $(CROSS_COMPILE)objdump

INCDIRS 		:= imx6ul \
				   bsp/clk \
				   bsp/led \
				   bsp/delay  \
				   bsp/beep \
				   bsp/gpio \
				   bsp/key
				   			   
SRCDIRS			:= project \
				   bsp/clk \
				   bsp/led \
				   bsp/delay \
				   bsp/beep \
				   bsp/gpio \
				   bsp/key
				   
				   
INCLUDE			:= $(patsubst %, -I %, $(INCDIRS))

SFILES			:= $(foreach dir, $(SRCDIRS), $(wildcard $(dir)/*.S))
CFILES			:= $(foreach dir, $(SRCDIRS), $(wildcard $(dir)/*.c))

SFILENDIR		:= $(notdir  $(SFILES))
CFILENDIR		:= $(notdir  $(CFILES))

SOBJS			:= $(patsubst %, obj/%, $(SFILENDIR:.S=.o))
COBJS			:= $(patsubst %, obj/%, $(CFILENDIR:.c=.o))
OBJS			:= $(SOBJS) $(COBJS)

VPATH			:= $(SRCDIRS)

.PHONY: clean
	
$(TARGET).bin : $(OBJS)
	$(LD) -Timx6ul.lds -o $(TARGET).elf $^
	$(OBJCOPY) -O binary -S $(TARGET).elf [email protected]
	$(OBJDUMP) -D -m arm $(TARGET).elf > $(TARGET).dis

$(SOBJS) : obj/%.o : %.S
	$(CC) -Wall -nostdlib -c -O2  $(INCLUDE) -o [email protected] $<

$(COBJS) : obj/%.o : %.c
	$(CC) -Wall -nostdlib -c -O2  $(INCLUDE) -o [email protected] $<
	
clean:
	rm -rf $(TARGET).elf $(TARGET).dis $(TARGET).bin $(COBJS) $(SOBJS)	

3、 ... and 、 eliminate BSS

Plus clear BSS paragraph , The code doesn't run
__bss_start = 0X87800289. about 32 Bit SOC Come on , The general visit is 4 Byte access .0X0,0X4,0X8,0XC. The chip is processed with 4 Byte access , So it will come from 0X878000288 Start clearing BSS paragraph . However 0X878000288 Do not belong to BSS paragraph . So we need to deal with __bss_start Carry out four byte alignment . According to the principle of four bytes ,__bss_start=0X8780028C. So you need to set __bss_start Align four bytes .

Make changes in the link script

SECTIONS{
	. = 0X87800000;
	.text :
	{
		obj/start.o 
		*(.text)
	}
	.rodata ALIGN(4) : {*(.rodata*)}     
	.data ALIGN(4)   : { *(.data) }    
	__bss_start = .;    
	.bss ALIGN(4)  : { *(.bss)  *(COMMON) }    
	__bss_end = .;
}