单片机c语言外部变量问题

你在头文件中定义类型
typedef union unxs
{
struct stxs
{
unsigned char bit0: 1;
unsigned char bit1: 1;
unsigned char bit2: 1;
unsigned char bit3: 1;
unsigned char bit4: 1;
unsigned char bit5: 1;
unsigned char bit6: 1;
unsigned char bit7: 1;
} jg_byte;
unsigned char gy_byte;
} UNXS;

然后在C文件里定义变量
UNXS lcd_wz;

最在在要引用的地方或是头文件里声明一下
extern UNXS lcd_wz;就可以了。

#IFNDEF ABC_UNION
#DEFINE ABC_UNION
union unxs
{
struct stxs
{
unsigned char bit0: 1;
unsigned char bit1: 1;
unsigned char bit2: 1;
unsigned char bit3: 1;
unsigned char bit4: 1;
unsigned char bit5: 1;
unsigned char bit6: 1;
unsigned char bit7: 1;
} jg_byte;
unsigned char gy_byte;
} lcd_wz;

#ENDIF