ningling_21 

 遇到奇怪问题
遇到奇怪问题
我用AT89S52和DS1307（I2C接口的时钟芯片）和LCD模块做时钟显示，配有按键，但是有个怪现象，显示的时间是从时钟芯片中读出的，但是走时2个小时就会有时间偏差，一般会有50多分钟，走6－7个小时，时间停住了，硬件实在没什么问题，希望高手指点迷津，不胜感激。
I2C读写代码如下：
P3.0-------SCL
P3.1-------SDA
；－－－－－－－－－－－－－－－－－
wr_byte:  mov r7,#8
          clr c
          mov a,i2c_wdata
          rlc a
   wlp:   jnb cy,wr00
          setb vsda
          ajmp wp1
   wr00:  clr vsda
   wp1:   nop
          nop                         ;add 2008-4-30
          nop                         ;add 2008-4-30
          setb vscl
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-4-30
          nop                         ;add 2008-4-30
          clr vscl
          nop
          rlc a
          djnz r7,wlp
          setb vsda
          nop
          setb vscl
          clr flag1  ;nop
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop      
          nop      
          mov c,vsda;
          nop       
          jnc cend0 ;
          setb flag1 ;
cend0:   clr vscl  
          ret
；－－－－－－－－－－－－－－－－－－－－－－－

read_data:clr c
          mov i2c_rdata,#00   
          mov r7,#8
  lop1:   setb vsda            ;input
          nop
          nop                  ;add 2008-4-30
          setb vscl
          nop                  ;nop
          nop                  ;add 2008-4-30
          nop                  ;nop
          nop                  ;nop
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                  ;nop
          mov c,vsda           ;start read
          mov a,i2c_rdata      ;nop
          rlc a                ;nop
          mov i2c_rdata,a      ;nop
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop                         ;add 2008-5-15
          nop
          clr vscl             ;
          nop                  ;nop
          djnz r7,lop1
          ret

发表时间:2008年7月2日22:47:59