HEX to DEC conversion question (BCD?)

T&E Engineer

As many of you know I have been working on updating my 16x16 tricolored LED Matrix RTC.

I have added a 74HC165 to my 16x16 tricolored LED Matrix RTC circuit because there was only 3 I/O lines left on my SX52 and I needed at least 4 pushbuttons to set the date and time on this.

However, as it stands at the moment I can increment and decrement a hex number on the display and even watch it scroll by while updating it. I'm not sure if I want to have it scroll while updating the time or date but for now it is ok.

The problem I need help in understanding or need a solution to is as follows:

If I start with a TIMESET = 34 variable declaration, the display routine keeps it in·hex so that·when incrementing the TIMESET variable it·gets displayed as 34 35 36 37 38 39 3A 3B ....

Currently I have tried JonnyMac's DEC2BCD routine which I have seen good results on in the past. However, in this application I don't know how to link them together right. I·have tried and only get the last digit scrolled like 4 5 6 7 8 9 A B ... so something on my end is not right.

What do I have to do to get past this·so that it gets incremented as 34 35 36 37 38 39 40 41 .. ?

I looks like I need to increment a decimal (or maybe BCD) number·but the display routine needs a hex number.

I have attached my code for anyone to follow.

Thanks.



Post Edited (T&E Engineer) : 5/18/2007 6:49:40 PM GMT

Bean

' Increment timeSet (BCD)
temp = timeSet AND $0F
IF temp = 9 THEN
· timeSet = timeSet + 7
ELSE
· INC timeSet
ENDIF


Bean.

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JonnyMac

Here's Bean's code wrapped up in a function so that it can be called from anywhere and applied to any [noparse][[/noparse]byte] variable -- this also checks for and handles 10's rolloever.

FUNC INC_BCD
  tmpB1 = __PARAM1                              ' save parameter
  tmpB2 = tmpB1 & $0F                           ' extract low nib
  IF tmpB2 < $9 THEN
    INC tmpB1                                   ' inc ones
  ELSE
    tmpB1 = tmpB1 + 7                           ' clear ones, inc tens
    tmpB2 = tmpB1 & $F0                         ' extract high nib
    IF tmpB2 > $90 THEN                         ' check for 10s rollover
      tmpB1 = $00
    ENDIF
  ENDIF
  RETURN tmpB1
  ENDFUNC

T&E Engineer

Thanks to both of you. I will look at this tonight.