time trouble!!

[Guest]

hi everyone!

i am experiencing some trouble in interfacing ds1302 RTC to Pic16f877. i am able to set the time correctly, and also read the correct time ever 5 seconds (see the code below), but when i use to the battery backed mode (i.e +5v power is available to RTC but not to the PIC ) then the time seems to lag behind. i mean, whenever i read the time from the controller at random intervals it always seems to start from 0 seconds so the format is hh:mm:00 and then it moves on. Also it sometimes seems to start the time with the last displayed value i.e lets say it displays the time 12:20:32, after this if i take away the power of the PIC (RTC running on backup power +5v) and after sometime when i check the time again it sometimes gives me the exact same time as before so lets say after 2 minutes when i recheck the time (by using 'rtc_get_time( hour, min, sec )' command) i sometimes get the reading 12:20:32 which is the same as before. i must stress though that both these phenomenons (time not updating and seconds count zero) are random. sometimes the RTC works perfectly, can any one please explain this strange behaviour.

My second question is that, is there any way to convert the time(hh:mm:ss) and date (day/month/year) to strings that can be concatenated with any other string data type (so i want to convert the hrs and minutes etc from the format %2X into string data type).

here is the code that i am using:

[PCM programmer]

[Guest]

hi everyone!


is there any way to convert the time(hh:mm:ss) and date (day/month/year) which is presumably in BCD format into strings that can be concatenated with any other string data type (so i want to convert the hrs and minutes etc from the format %2X into string data type).

here is the code that i am using:

Code:

#include <16F877.h>
#device *=16 ADC=10
#include <stdlib.h>
#USE DELAY (CLOCK=4000000)
#include <DS1302.C>
#fuses XT,NOWDT,NOLVP
#use rs232(baud=4800,xmit=pin_b1,rcv=pin_b2,parity=N,stream=pc)


byte get_bcd()
{
char first,second;

do
{
first=fgetc(pc);
}

while ((first<'0') || (first>'9'));


fprintf(pc,"first = %C",first);

first-='0';

do
{
second=fgetc(pc);
}

while ((second<'0') || (second>'9'));


fprintf(pc,"second = %C",second);

return((first<<4)|(second-'0'));
}

void set_clock()
{
byte day,mth,year,dow,hour,min;

fprintf(pc,"\fYear 20: ");

year=get_bcd();

fprintf(pc,"\fMonth: ");

mth=get_bcd();

fprintf(pc,"\fDay: ");

day=get_bcd();

fprintf(pc,"\fWeekday 1-7: ");

dow=get_bcd();

fprintf(pc,"\fHour: ");

hour=get_bcd();

fprintf(pc,"\fMin: ");

min=get_bcd();

rtc_set_datetime(day,mth,year,dow,hour,min);
}



void main()
{
byte day,mth,year,dow,hour,min,sec;

rtc_init();

fprintf(pc,"start");

set_clock();

while(1)

{

rtc_get_date( day, mth, year, dow);

rtc_get_time( hour, min, sec );

fprintf(pc,"\n%2X/%2X/%2X\n%2X:%2X:%2X",day,mth,year,hour,min,sec);

fprintf(pc,"\n",dow);

delay_ms(5000);

}

}

[PCM programmer]