RTC bcd->binary in 24 hour modes

[Oli]

Hi All

I'm using the DS1337 - appears to work fine. I based my code loosely on the driver here:

http://www.ccsinfo.com/forum/viewtopic.php?t=28366&highlight=ds1337

my question relates to the HOUR registers. In the datasheet bits 0-3 set the hour. Bits 4 and 5 each indicate an additional 10 hours. Bit 6 is the 12/ !24 hour setting.

All of the drivers I have seen on the web read the hours value using a straight BCD to binary conversion, meaning that if the time is (in 24hr format) 10pm == 22:00

then the register reads 00110010 == 0x32 == 50 decimal

then that converts from BCD to binary as an hour of 32 o'clock, which is clearly wrong. In the linked driver, this line reads the register:

[FvM]

You misunderstood the coding of hour tens. 22h is actually coded as 0x22, not 0x32. The tens field has
regular BCD encoding as all others, too.