how can I caculate with numbers bigger than a word using 16F88 ?

[Charles Linquis]

I'm trying to rid the world of 16F chips, but try this

http://www.picbasic.co.uk/forum/show...ght=n-bit_math

[Jerson]

What is x20?
what is f0?
what is x?

A little more detail and it is possible that a different solution exists.

The last time I did something similar, I had a pulses per mile count. After that the mile count would increase by 1. To handle numbers as big as 99999999 you can do it in code like I did

Pseudo code begins

miles[4]    var    byte         ' lsb to msb

        on input pulse,  pulses=pulses+1
        
        if pulses >= Pulsespermile
              pulses = 0                               ' start counting again till we reach pulses per mile

              miles[0] = miles[0]+1
              if miles[0] > 99 then
                   miles[0]  =0
                   miles[1] = miles[1]+1
                   if miles[1] > 99 then
                        miles[1] = 0
                        miles[2] = miles[2]+1
                        if miles[2] > 99 then
                              miles[2] = 0
                              miles[3] = miles[3]+1
                              if miles[3] > 99 then
                                   miles[3] = 0   ' roll over to all zero
                              endif
                        endif
                    endif
              endif
       endif

Now, displaying this is easy.

      Num = miles[0] dig 1                ' first digit to display
      digitpos = 0
      gosub displaynum                   ' show the number

      Num = miles[0] dig 0                ' 2nd digit to display
      digitpos = 1
      gosub displaynum                   ' show the number

      Num = miles[1] dig 1                ' 3rd digit to display
      digitpos = 2
      gosub displaynum                   ' show the number

      Num = miles[1] dig 0                ' 4th digit to display
      digitpos = 3
      gosub displaynum                   ' show the number

and so on

[NullDevice]

I'm trying to rid the world of 16F chips...

I'm with you, Charles, but is there a PIC18 that is nearly the same price as a PIC16F88? I'm doing a low cost consumer product right now where 40 cents makes a big difference. Until that time, that evil PIC16F architecture lives on.

[Charles Linquis]

In some cases,(like high-volume applications), the 16F series makes sense. But too often I see people that work hours (or tens of hours) longer to get something to work because they started out with an inadequate chip on a one-off project.

[rmteo]

I'm with you, Charles, but is there a PIC18 that is nearly the same price as a PIC16F88? I'm doing a low cost consumer product right now where 40 cents makes a big difference. Until that time, that evil PIC16F architecture lives on.

According to here PIC16F88 the lowest cost device is $2.20 - if you go here PIC18 Product Family and do a sort on ascending price, you will find about 45 PIC18's that cost less than a PIC16F88. That said, I use several competitive 32-bit devices that are about half that price.

[Darrel Taylor]

Not sure, but maybe you can just change 1-line.

'---[INT - interrupt handler]---------------------------------------------------
ToggleLED1:
   cnt = cnt +1
   cntb = cnt * 20 ; could be * 1000
   meter = DIV32 f0 
   If meter = x Then  
     meter = 0
     km = km + 1
     cnt = 0
   Endif
@ INT_RETURN

Depends on what f0 and x are.

[BigWumpus]

If you are looking for costs ... forget all this old 16F... or 18F...-devices.

Take new cheap dsPic33 or ...J... or ...K... -devices.
The new devices are very cheap, the old stuff is expensive !!!!

[Bill Legge]

Not an economic solution but great fun is the 'floating point co-processor' from Micromega. Costs about $20. the free IDE make developing the code a doddle.

Regards Bill Legge