Working with indivividual bytes of an array

[sougata]

Hi,

As far as I remember the RTC holds the time in packed BCD format. That is the upper nibble is the tens and the lower nibble is the unit. So the formula to convert it would be
Real_Hours = (10* hour_tens)+ hour_units
In PBP this would be :

    CLOCK_TMP1 = (HOURS >> 4) * 10              ' PROCESS 10s BCD
    HOURS    = HOURS & %00001111                 ' PROCESS 1s BCD
    HOURS    = CLOCK_TMP1+ HOURS                ' ADD BOTH TO GET BINARY

Where CLOCK_TMP1 is a temporary variable. You can do it in one line to. I broke up the thing to make it more readable

While working on a PCF8563 RTC chip I noticed that the unused bits in the memory map are not always "zero". Thus it is good idea to shred off the bits not used and make them zero manually. Like:

      HOURS   = HOURS     & %00111111             ' clear unused bits
      MINUTES = MINUTES & %01111111             ' clear unused bits

Happy New Year

[sayzer]

In addition to sougata's, here is a conversion from Melanie's.
You need to convert your decimal values to HEX values and then you can write the HEX values to your RTC chip.

DecVal = HOUR
GOSUB ConvertBCD
HOUR = HEXVal

'Now you set your RTC chip with this new HOUR variable (which is now in HEX).


ConvertBCD:                            
        HEXVal = DecVal DIG 1
	HEXVal = HEXVal <<4
	HEXVal = HEXVal + DecVal DIG 0
	RETURN

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Edit: also take a look at this post here: http://www.picbasic.co.uk/forum/showthread.php?t=110

[J_norrie]

Thanks again Guy's got the clock working fine writing and reading from the RTC chip.