Linear acceleration ramp

[SteveB]

Here is a start (not tested!). But it should get you going in the right direction. I only included the acceleration stuff to keep the logic simpler.
You will need the include files (Get Darrel's from http://darreltaylor.com/DT_INTS-18/downloads.html), and make sure the file names match.

' PIC18F4431 initializationDEFINE OSC 40      
DEFINE LCD_DREG PORTD
DEFINE LCD_EREG PORTB
DEFINE LCD_RSREG PORTB
DEFINE LCD_EBIT 6
DEFINE LCD_RSBIT 7

tacc var BYTE
tdec var BYTE
cacc var word
cdec var word  
ref var word
fmin var word
freq var WORD

cacc_div VAR BYTE
cdec_div VAR BYTE

tacc=1
tdec=10
fmin=10
ref=1200

PAUSE 4000
LCDOUT $fe,$1

INCLUDE "DT_INTS-18.bas"
INCLUDE "ReEnterPBP-18.bas"
INCLUDE "TimerControl.pbp"  ; Timer Control Routines

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   TMR1_INT,  _UpdateTickCount,   PBP,  yes
    endm
    INT_CREATE            ; Creates the interrupt processor
ENDASM

@   INT_ENABLE  TMR1_INT  ; Enable Timer 1 Interrupts  

GOSUB ResetTime           ' Reset Timer and mSec_Ticks = 0

IF tacc > 65 THEN
   cacc_div = 10
ELSE 
   cacc_div = 1     
ENDIF 

cacc = ((1000/cacc_div) * tacc) / (ref - fmin)
GOSUB StartTimer          ' Start Counting mSec_Ticks


Main:


     IF mSec_Ticks > (cacc * cacc_div) THEN
        IF freq < ref THEN freq = freq + 1
        mSec_Ticks = mSec_Ticks - (cacc * cacc_div)
        IF freq >= ref THEN
           GOSUB StopTimer
           GOSUB ResetTime
     ENDIF
     
   LCDOUT $fe,$2,DEC5 freq          
   IF PORTC.0=%1 THEN ref=500


GOTO Main

I may not be much use the next couple of days, but the building blocks are here (hopefully without too many errors/typos)