AVR单片机RX8025的C语言读写程序解析

#include <iom128v.h>   

#include <macros.h>  
int time1s=0;              //1s定时   
unsigned char S1BZ=0;      //1s标志   
unsigned char TWIBUSY=0;  //TWI忙标志   
unsigned char RTC_W_R=1;  //RTC_W_R=1表示读RX_8025,RTC_W_R=0表示写RX_8025   
unsigned char TWI_BUF_W[11]={   
   0x64,0xE0,0x20,0x20,0x40,0x57,0x23,0x04,0x31,0x05,0x08}; //实时时钟写缓冲区   
/*{SLA+W,从寄存器E开始写,控制字1,控制字2,秒,分,时,星期,日,月,年}*/   
unsigned char TWI_BUF_R[10]={0x64,0x00,0x65}; //实时时钟读缓冲区   
unsigned char twi_cmd_counter=1; //twi 命令计数器   
unsigned char twi_dat_counter=1; //twi 数据计数器   
unsigned char twi_buf_ptr=0;     //实时时钟数据缓冲区指针   
unsigned char twi_stp=1;         //twi步骤计数   
unsigned char twi_buf_num=0;     //实时时钟缓冲区大小   
unsigned char data_time[12]={1,2,3,4,5,6,7,8,9,0,2,3};        //日期时间显示缓冲区   
   
void port_init(void)   
{   
 PORTA = 0xFF;      //端口A用于指示灯,输出,初始值全为1   
 DDRA  = 0xFF;   
 PORTB = 0xFF;     //PB0~PB3用于SPI,PB0为ATT7022B的片选信号;PB4用于指示灯   
 DDRB  = 0xF7;     //PB5控制蜂鸣器,PB6作为AT45DB161D的片选,PB7控制2576    
 PORTC = 0x00;     //和液晶屏数据位相连接   
 DDRC  = 0xFF;     //初始化为输出   
 PORTD = 0xC0;     //PD0~1用于I2C,PD2~3用于GTM900,PD4~5悬空,   
 DDRD  = 0xC0;     //PD6-CS1液晶屏左半屏片选,PD7-CS2液晶屏右半屏片选,初始化为输出   
 PORTE = 0xFC;     //PE0~1用于MAX232,品;PE2~6用于键盘,初始化为输入   
 DDRE  = 0x03;     //PE7-PFO 接MAX705(电源故障输出),初始化为输入   

 PORTF = 0x08;     //PF0~2悬空,PF3接AT45DB161D RDY信号,输入   
 DDRF  = 0xF7;     //PF4~7用于JTAG   
 PORTG = 0x0F;     //PG0-RS,PG1-R/W.PG2-E,PG3-WDI(For MAX705,监视电压跟踪输入)   
 DDRG  = 0x1F;     //PG0~3配置为输出,PG4悬空   
}   
//TIMER0 initialize - prescale:64   
// WGM: Normal   
// desired value: 1mSec   
// actual value:  1.000mSec (0.0%)   
void timer0_init(void)               //定时器0初始化   
{   
 TCCR0 = 0x00; //stop   
 ASSR  = 0x00; //set async mode   
 TCNT0 = 0x45; //set count   
 OCR0  = 0xBB;   
 TCCR0 = 0x03; //start timer   
}   
   
//定时器0中断服务程序   
#pragma interrupt_handler timer0_ovf_isr:17   
void timer0_ovf_isr(void)   
{   
 TCNT0 = 0x45; //reload counter value   
 if(time1s<1000)   
 {   
 time1s++;   
 }   
 else   
     {   
        S1BZ=1;    //1秒标志用于实时时钟的读写