Comparing output from DS1307

[johnl69]

Can I directly compare the BCD output from a ds1307 with another register or do I need to convert it to binary first?

i have a program that takes the time from the RTC and compares it with some "alarm" registrys that I have set up;

// ****  Check Blue timer ***********
    if (((hour >= ON_BLUE_hr)&&(minute >= ON_BLUE_min))&&((hour <= OFF_BLUE_hr)&&(minute <= OFF_BLUE_min)))
    {
        BLUE_L = 1;
    }
    else
    {
        BLUE_L = 0;
    }

the ON and OFF registry are set at;

unsigned int ON_BLUE_hr = 0b00001000;
unsigned int ON_BLUE_min = 0b00000000;

unsigned int ON_MAIN_hr = 0b00001001;
unsigned int ON_MAIN_min = 0b00000000;

unsigned int OFF_MAIN_hr = 0b00100000;
unsigned int OFF_MAIN_min = 0b00000000;

unsigned int OFF_BLUE_hr = 0b00100000;
unsigned int OFF_BLUE_min = 0b00110000;

the alarm time display correctly on an lcd but the but the light only turn on when they should.

 

[Nigel Goodwin]

You might like to have a look here:

http://www.engscope.com/pic-example-codes/real-time-clock-and-calendar/

This uses a data structure to easily compare two date/times.

 

[johnl69]

You might like to have a look here:

http://www.engscope.com/pic-example-codes/real-time-clock-and-calendar/

This uses a data structure to easily compare two date/times.

From what I gather ( i may be wrong) that routine has the alarm triggering at a set time/date which isn't what I'm after I need the alarm to be on between the 2 times incase the power is turned off then the light will go back to what ever state it should be at when the power turn on again.

 

[granddad]

I compare hours from DS1307 to 'action times' no problems ,, I usually use BCD / hex notation as 0x10 as 10 hours , is the DS set for 12 or 24 hr.

 

[johnl69]

I compare hours from DS1307 to 'action times' no problems ,, I usually use BCD / hex notation as 0x10 as 10 hours , is the DS set for 12 or 24 hr.

24hr.

A strange thing happened at 20:00 the lights turned on and then 1 minute later they all turned off

 

[johnl69]

I just changed it to

hr = hour & 0b00111111;

// ****  Check Blue timer ***********
   if (((hr >= ON_BLUE_hr)&&(minute >= ON_BLUE_min))&&((hr <= OFF_BLUE_hr)&&(minute <= OFF_BLUE_min)))
   {
        BLUE_L = 1;
   }
   else
   {
        BLUE_L = 0;
   }

Just to make sure there are no extra 1's being read from the extra bits but it's the same.[/code]

 

[Ian Rogers]

My read / write RTC routines always have built in " convert to english" and "convert back to nonsense" routines so its never an issue...

 

[johnl69]

My read / write RTC routines always have built in " convert to english" and "convert back to nonsense" routines so its never an issue...

I'll do a BCD to binary conversion on it tomorrow see if it makes a difference.

21:00 when the lights should turn off the blue light came on for 1 minute. it only seem to be working on the set times not between them??

 

[johnl69]

Sorted now, not sure whether it was necisary to convert to binary but it does make it easier to set the times

    binary_hr = BCD2Binary(hr);
    binary_min = BCD2Binary(minute);

    if ((binary_hr >= binary_blue_off_hr)&&(binary_min >= binary_blue_off_min))
    {
        BLUE_L = 0;
    }
    else if ((binary_hr >= binary_blue_on_hr)&&(binary_min >= binary_blue_on_min))
    {
        BLUE_L = 1;
    }