PICC支持下的C程序代码中一定要包含pic.h头文件，该文件安装在HT-PIC\include目录下。它是很多头文件的集合，C编译器在pic.h中根据用户选择的芯片自动载入相应的其它头文件，例如用户选择的芯片是PIC16F877，则pic.h会把pic1687x.h载入；例如用户选择的芯片是PIC16F877A，则pic.h会把pic168xa.h载入。载入的头文件中其实是声明芯片的寄存器和一些函数。例如以下程序片段：

static volatile unsigned char PORTA@ 0x05;

static volatile unsigned char PORTB@ 0x06;

static        unsigned char bank1 OPTION@ 0x81;

static        unsigned char bank1 TRISA@0x85;

static        unsigned char bank1 TRISB @0x86;

@符号表示地址的意思。这些声明和PIC汇编中的定义寄存器是差不多的。

例如：

TMR0 EQU 0x01;

PCL EQU 0x02;

STATUS EQU 0X03;

对于特殊功能寄存器的位地址在头文件中也有定义，比如PORTB端口的位地址定义如下：

/*   PORTB bits   */

static volatile bit  RB7  @ (unsigned)&PORTB*8+7;

static volatile bit  RB6  @ (unsigned)&PORTB*8+6;

static volatile bit  RB5  @ (unsigned)&PORTB*8+5;

static volatile bit  RB4  @ (unsigned)&PORTB*8+4;

static volatile bit  RB3  @ (unsigned)&PORTB*8+3;

static volatile bit  RB2  @ (unsigned)&PORTB*8+2;

static volatile bit  RB1  @ (unsigned)&PORTB*8+l;

static volatile bit  RB0  @ (unsigned)&PORTB*8+0;

其中RB7代表PORTB的bit7。

我们可以模仿pic.h文件的定义方法定义RAM中文件寄存器的方法，定义bank0的20h，21h，22h为文件寄存器以及他们的位地址。

假设我们把

20h取名RAM20H，其位地址分别是RAM20H7~RAM20H0

21h取名RAM21H，其位地址分别是RAM21H7~RAM21H0

22h取名RAM22H，其位地址分别是RAM22H7~RAM22H0

定义如下：

static volatile unsigned char RAM20H @0x20;

static volatile unsigned char RAM21H @0x21;

static volatile unsigned char RAM22H @0x22;

RAM20H的位地址定义如下：

static volatile bit RAM20H7 @(unsigned)&RAM20H*8+7;

static volatile bit RAM20H6 @(unsigned)&RAM20H*8+6;

static volatile bit RAM20H5 @(unsigned)&RAM20H*8+5;

static volatile bit RAM20H4 @(unsigned)&RAM20H*8+4;

static volatile bit RAM20H3 @(unsigned)&RAM20H*8+3;

static volatile bit RAM20H2 @(unsigned)&RAM20H*8+2;

static volatile bit RAM20H1 @(unsigned)&RAM20H*8+1;

static volatile bit RAM20H0 @(unsigned)&RAM20H*8+0; 

RAH21H和RAH22H的位地址也可以类似定义：

static volatile bit RAM21H7 @(unsigned)&RAM21H*8+7;

static volatile bit RAM21H6 @(unsigned)&RAM21H*8+6;

static volatile bit RAM21H5 @(unsigned)&RAM21H*8+5;

static volatile bit RAM21H4 @(unsigned)&RAM21H*8+4;

static volatile bit RAM21H3 @(unsigned)&RAM21H*8+3;

static volatile bit RAM21H2 @(unsigned)&RAM21H*8+2;

static volatile bit RAM21H1 @(unsigned)&RAM21H*8+1;

static volatile bit RAM21H0 @(unsigned)&RAM21H*8+0;

static volatile bit RAM22H7 @(unsigned)&RAM22H*8+7;

static volatile bit RAM22H6 @(unsigned)&RAM22H*8+6;

static volatile bit RAM22H5 @(unsigned)&RAM22H*8+5;

static volatile bit RAM22H4 @(unsigned)&RAM22H*8+4;

static volatile bit RAM22H3 @(unsigned)&RAM22H*8+3;

static volatile bit RAM22H2 @(unsigned)&RAM22H*8+2;

static volatile bit RAM22H1 @(unsigned)&RAM22H*8+1;

static volatile bit RAM22H0 @(unsigned)&RAM22H*8+0;

将这些定义加入到相应的头文件中，或者直接写在源程序中，这样就可以直接对通过变量RAM20H对bank0的20h单元进行字节操作，可以通过RAM20H7~RAM20H0对bank0的20h单元进行位操作。例如：

#include

main()

{  

RAM20H=0x20;   //把0x20赋值给20h

RAM21H=0x21;   //把0x21赋值给21h

RAM22H= RAM20H+ RAM21H;

while(1) {  ;   }

}

以上程序假设RAM20H、RAM21H和RAM22H的声明已经加入到相应的头文件中，那么在源程序中就可以直接使用。