ds1307 "day of week" reading problem

[cnsnt]

hi all.I have a problem for ds1307.I'm using following ds1307 driver but ı can not read "day of week"information.LCD always writing "00".. I can read other informations.could somebody help me? THANKS

DRIVER

// ds1307.c -- Functions for the Dallas Semiconductor DS1307
// real time clock and NVRAM chip.
//
// The DS1307 uses BCD as its internal format, but we use it
// in binary format, outside of this module. So we have code
// to convert to/from BCD to binary in the functions below.

//----------------------------------------------------------------------
// Set the date and time.
/*
The registers inside the ds1307 are in this format. The values are in BCD.

DS1307_SECONDS_REG 0
DS1307_MINUTES_REG 1
DS1307_HOURS_REG 2
DS1307_DAY_OF_WEEK_REG 3 // We don't use this register. Set it to 0.
DS1307_DATE_REG 4
DS1307_MONTH_REG 5
DS1307_YEAR_REG 6
*/

void ds1307_set_date_time(void)
{
char i;
// Convert the binary ds1307 data, which is passed in a global array,
// into bcd data. Store it in the same array.

/*for(i = 0; i <7>= 10)
{
temp -= 10;
retval += 0x10;
}
else // Get the ones digit by adding the remainder.
{
retval += temp;
break;
}
}

return(retval);
}


//--------------------------------------------------------------------------
// This function converts an 8 bit BCD value to an 8 bit binary value.
// The input range must be from 00 to 99.

char bcd2bin(char bcd_value)
{
char temp;

temp = bcd_value;
temp << 1; // Shifting upper digit right by 1 is same as mult. by 8
temp &= 0x78; // Isolate the bits for the upper digit

// Now return: (Tens *8) + (Tens *2) + Ones

return(temp + (temp << 2) + (bcd_value & 0x0f));

}


SOURCE CODE BLOCK
int dow;
while(1)
{
dow=(gca_ds1307_regs[3]);
ds1307_read_date_time();
lcd_init();
printf(lcd_putc,"\n%2X",dow);
}

[cnsnt]

also I wrote different values to for date in ds1307 but day of week didn't changed.

[Eugeneo]

This is what I used

[PCM programmer]

To cnsnt:

[Eugeneo]

Got it. Thanks

[cnsnt]

PCM programmer I didn't understand what you wrote.can you explane it?

[Douglas Kennedy]

Many would expect that encapsulating code with the code end code buttons is all that is needed to be done to post code. Surprise!! unless you also disable HTML the code won't post correctly. It's quirky but that's just the way it works

[ckielstra]

Eugeneo,
Your code fragment is still messed up and was originally posted in the code library by Aurelian Nichita.
When re-using code it is nice to give the original poster credit for his work.

[Douglas Kennedy]

Basically this is modulo 7 arithmetic with a bit of quirkiness for Feb29 during leap years. val=yr+yr/4 increments one every year and 2 if the year was a leap year. A regular year has 365 days or 365 modulo7 =1 hence we add one each year and one more if the year (leap) has 366 days.
That puts the routine a head of itself during jan and feb of an actual leap year hence the adjusting down of one. From the point of view of modulo 7 both 7 and 0 are the same so if the result is 0 it is set to 7 (sunday) Now jan1 2001 is a monday so table[0] needs to be 6 so year(=01)+day(=01)=2+6 =8mod 7=1=Monday add 31 days for jan
31 mod 7 is 3 table[0]=6 so table[1]=6+3=9 9 mod 7 is 2 (table[1]=2) and so on.
Now the table could be developed for any starting situation but 1/1/01 makes for easy calculation. There is no provision made for centuries not being leap years and 400 year centuries being leap years hence the 2099
restriction. I believe the code below works but if it causes you to miss your [spam] anniversary please don't blame me.

[cnsnt]

I solved problem thank you for all..