PIC单片机CCS之C语言(#IF,#ENDIF的用法)

串转换成整型数送给i

return(i);

}

signed long get_long() {

char s[7]; //声明字符型数组s[7]

signed long l; //声明有符号长整型变量l

get_string(s, 7); //从RS232口读7个字节,存储到s数组中

l=atol(s); //将数组s[]的字符串转换成长整型数送给l

return(l);

}

float get_float() {

char s[20]; //声明字符型数组s[7]

float f; //声明符点型变量l

get_string(s, 20); //从RS232口读20个字节,存储到s数组中

f = atof(s); //将数组s[]的字符串转换成符点数送给f

return(f);

}

#endif //结束if定义

文件: 2416.c如下:

//// Library for a MicroChip 24LC16B ////

//// init_ext_eeprom(); Call before the other functions are used ////

//// write_ext_eeprom(a, d); Write the byte d to the address a ////

//// d = read_ext_eeprom(a); Read the byte d from the address a ////

//// b = ext_eeprom_ready(); Returns TRUE if the eeprom is ready ////

//// to receive opcodes ////

//// The main program may define EEPROM_SDA ////

//// and EEPROM_SCL to override the defaults below. ////

//// Pin Layout ////

//// ----------------------------------------------------------- ////

//// | | ////

//// | 1: NC Not Connected | 8: VCC +5V | ////

//// | 2: NC Not Connected | 7: WP GND | ////

//// | 3: NC Not Connected | 6: SCL EEPROM_SCL and Pull-Up | ////

//// | 4: VSS GND | 5: SDA EEPROM_SDA and Pull-Up | ////

//// ----------------------------------------------------------- ////

#ifndef EEPROM_SDA //若没有定义EEPROM_SDA,则执行下面

#define EEPROM_SDA PIN_C4 //用EEPROM_SDA代替PIN_C4

#define EEPROM_SCL PIN_C3 //用EEPROM_SCL代替PIN_C3

#endif //结束if定义

#use i2c(master, sda=EEPROM_SDA, scl=EEPROM_SCL)

// master设置成主机方式

//除非指定了FORCE_HW,否则会产生模拟I2C的软件函数.

//使能I2C_START, I2C_STOP直到下一个#USE I2C的出现为止.

//使能I2C_READ, I2C_WRITE直到下一个#USE I2C的出现为止.

//使能I2C_POLL直到下一个#USE I2C的出现为止.

//指定sda脚为EEPROM_SDA, 指定scl脚为EEPROM_SCL

#define EEPROM_ADDRESS long int //用EEPROM_ADDRESS代替long int

#define EEPROM_SIZE 2048 //用EEPROM_SIZE代替2048

void init_ext_eeprom() {

output_float(EEPROM_SCL); //将EEPROM_SCL引脚设为输入,开集电极连接

output_float(EEPROM_SDA); //将EEPROM_SDA引脚设为输入,开集电极连接

}

BOOLEAN ext_eeprom_ready() {

int1 ack; //声明位变量ack

i2c_start(); //发送启动条件

ack = i2c_write(0xa0); //发送从机地址0xa0;若ack=0,表示从机应答(ACK);

//若ack=1,表示从机不应答(NO ACK);

i2c_stop(); //发送停止条件

return !ack;

} // ext_eeprom_ready()函数,若返回1,表示从机准备好; 若返回0,表示从机忙或eeprom坏了

void write_ext_eeprom(long int address, BYTE data) {

while(!ext_eeprom_ready()); //若从机忙,则主机等待

i2c_start(); //发送启动条件

i2c_write( (0xa0|(BYTE)(address>>7))&0xfe); //发送命令字的高字节(发送写命令)

i2c_write(address); //发送命令字的低字节

i2c_write(data); //发送数据

i2c_stop(); //发送停止条件

}

BYTE read_ext_eeprom(long int address) {

BYTE data; //声明字节变量data

while(!ext_eeprom_ready()); //先发器件地址,若从机忙,则主机等待

i2c_start(); //在此处是:发送重新启动条件

i2c_write( (0xa0|(BYTE)(address>>7))&0xfe); //发送命令字的高字节(发送写命令)

i2c_write(address); //发送命令字的低字节

i2c_start(); //发送启动条件

i2c_write( (0xa0|(BYTE)(address>>7))|1); //发送命令字的高字节(发送读命令)

data=i2c_read(0); //读I2C数据,然后发送ack=0(不用从机应答)

i2c_stop(); //发送停止条件

return(data); //返回所读到的I2C数据

}

上面的例子主要用来读写24C16,通过PC机RS232进行验证