BCD Help Please!

[Graham Ogle]

I'm back again with another BCD question. I can convert a number to BCD or a decimal to two BCD nibbles. But I need each nibble to be to base 10, i.e. the range is from 0 to 9, not 0 to 15. How can this be done please?
Alternatively, since the decimal nibble is never greater than 9, can I map these 4 bits, to 4 output pins and another 4 bit nibble to another 4 output pins? I can set all pins to one nibble or the other, but not independently.
I am trying to control a frequency synthesiser which needs a programming number upto 15999. I am trying to replicate BCD thumbwheels which would show upto 15 on the most significant digit and 9's on the other 3.
Any help would be much appreciated.
Thanks

 

[BeanieBots]

Not really sure what you concern is?
Each nibble of a BCD number IS base 10. If it were not, it would simply be an 8-bit binary number.
You say you can convert to BCD, so simply do that for the lower 3 digits but just output the raw binary (0 to 15) for the last digit.
That assumes that you equipment will understand a value over 9 on one of its BCD inputs. Normally this would be done with two BCD wheels 0-9 and 0-1.

 

[Graham Ogle]

Thanks for the information. I think I've been going round the same loop so many times, I've got myself confused. I'll give it a go.
Thanks
Graham

 

[rfs]

Graham. Have a quick look at this nonsense.
It might help.
<code><pre><font size=2 face='Courier'>'to split ONE frequency into four separate values
'EACH value is a FOUR bit number
'I use w3 for the main input number
'b1, b2, b3, b4 were just easy values to remember, while working
'
'


let w3 = $F999 ' Input as HEX and you're halfway there. Change value to check.
'
'




'OR b7 = $F9 ' see Basic guide p6 ...
'and b6 = $99 ' It's the same thing, except longer to type.


'
sertxd (&quot;w3= &quot;,#w3,&quot; b7= &quot;,#b7,&quot; b6= &quot;,#b6, 13,10,13,10) ' Print a check.
Start new line
'


b1 = b7/16 'move bits 4 to the right
b2 = b7*16 'move bits 4 to the left' to remove bits 7-4
b2 = b2/16 'move bits 4 to the right

b3 = b6/16 'and again
b4 = b6*16
b4 = b4/16
'

sertxd (#b1, &quot; &quot;,#b2,&quot; &quot;,#b3,&quot; &quot;,#b4, 13,10) ' print a check
'

' And then remove MOST of this program
' and say
' pins = b7 do things. Then
' pins = b6

'Hope this MIGHT help </font></pre></code>






Edited by - rfs on 23/04/2006 20:28:30