Problem with DS1307 library

[GoogleCodeExporter]

What steps will reproduce the problem?
1. I wrote the attached code
2. worked well the first time
3. but, the next run, the clock loses the hour and seconds

What is the expected output? What do you see instead?

In the library code is wrong

procedure ds1307_init() is
   ds1307_write( 0x00 , 0 )                 -- Clk halt bit(7):0=ON 1=OFF
   ds1307_write( 0x07 , 0b_10010000 )    -- OSC ON
   ds1307_write( 0x02 , 0 )                 -- 24H mode
end procedure

It should be something like this:

procedure ds1307_init() is
    var byte value
    ds1307_read( 0x00, value)
    ds1307_write( 0x00 , value & 0x7F)          -- Clk halt bit(7):0=ON 1=OFF

    ds1307_read( 0x02, value)
    ds1307_write( 0x02 , value & 0xCF)          -- 24H mode bit(6)

    ds1307_write( 0x07 , 0b_00000000 )          -- OUT bit(7), SQWE bit(4), RS0=RS1=0 ->Freq

end procedure

Original issue reported on code.google.com by felixls....@gmail.com on 20 Jul 2011 at 5:43

[GoogleCodeExporter]

Fixed the initialization routine according to datasheet.

This library will be subject of revision with issue 185 (and 186).

Original comment by robhamerling on 24 Apr 2013 at 6:53

• Changed state: Fixed
• Added labels: Component-External

[GoogleCodeExporter]

This issue was prematurely marked as fixed. The switch in rtc_init() from 12- 
to 24-hour mode is incorrect in more than one way. 
Temporary fix: when the ds1307 is in 12-hour mode it is switched to 24-hour 
mode, but the hour value is left unchanged. So when the switch happens after 
midday the clock will be 12 hours off. When the clock is set right after the 
_rtc_init() it will remain to work correctly (provided it is not switched back 
to 12-hour mode!).

Original comment by robhamerling on 25 Apr 2013 at 8:13

• Changed state: Started