8051 with RTC DS12887 problem

[KlausST]

Hi,

as far as i can see you don´t use any of the three methods to prevent corrupt data.

--> I don´t think it is usefull to read the data at hig speed in an infinite loop.
Your code seems to read the data maybe thousand of times in a second and uptes the display at the same rate.

Do you have the interrrupt line connected from clock to controller?

Klaus

 

[MRgenius]

Hi,

as far as i can see you don´t use any of the three methods to prevent corrupt data.

--> I don´t think it is usefull to read the data at hig speed in an infinite loop.
Your code seems to read the data maybe thousand of times in a second and uptes the display at the same rate.

Do you have the interrrupt line connected from clock to controller?

Klaus

i added the first method as following but it result in more time error
weather i pooled on UF bit or IRQF
i thought i won't need the interrupt pin so i didn't connect it

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Code C - [expand]
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while(1)
{
if((XBYTE[12] & 0x10)== 0x10){  //looping on UF bit
    //if((XBYTE[12] & 0x80)== 0x80){  //looping on IRQF bit
    sec = XBYTE[0];
    min = XBYTE[2];
    hr  = XBYTE[4];
    day  = XBYTE[7];
    month= XBYTE[8];
    year = XBYTE[9];
        if(disp_f == 0){
          display(sec , min , hr);
            if(sec == 0x19)
            disp_f = 1;
        }
        else{
            display(year ,month ,day);
            if(sec == 0x39)
                 disp_f = 0;
        }
        XBYTE[12] = 0;
    }
}

---

 

[KlausST]

Hi,

XBYTE[12] = 0;

What´s this?

--> datasheet says:

All flag bits are cleared after Register C is read by the program

Klaus

 

[MRgenius]

Hi,
What´s this?
--> datasheet says:

Klaus

i found the datasheet says also at the end of method 1 description
If this interrupt is used, the IRQF bit in Register C should be cleared before leaving the interrupt routine.

besides i tried the code without this statement and it has no difference

 

[KlausST]

Hi,

If this interrupt is used, the IRQF bit in Register C should be cleared before leaving the interrupt routine.

True, but how to clear it.

Datasheet never mentiones that writing a "0" to the bit clears it.
It always says, that reading registerC clears it. Please do so.

It seems to be no "read/write" bit. Just read only, and the same it is cleared.

Klaus

 

[MRgenius]

Hi,


True, but how to clear it.

Datasheet never mentiones that writing a "0" to the bit clears it.
It always says, that reading registerC clears it. Please do so.

It seems to be no "read/write" bit. Just read only, and the same it is cleared.

Klaus

ok i removed this statement

- - - Updated - - -

To summarize:
i think my problem is that
1_ keep reading the RTC at high speed many times at each second
(any suggestions to solve this)
2_ using method 1 ... it seems i have to use the interrupt pin with it, and this method cann't be used without the interrupt pin .. please correct me if i'm mistaken

 

[FvM]

any suggestions to solve this

read the RTC at the lowest acceptable rate, controlled by a software timer.

 

[MRgenius]

read the RTC at the lowest acceptable rate, controlled by a software timer.

i mean by my question (any suggestion... ) how to control the rate as all RTC codes i met before were reading directly .. do i have to use MCU timer