Instant Interrupts - Revisited

[ScaleRobotics]

Thanks for the help Darrel.

I will look into it further. I had initialized stepcount to 32, then later to 8. Seems to get stuck after about two flashes of the led's.

Walter

[Darrel Taylor]

Maybe you need to set PCLATH before changing PCL?

[Bruce]

Walter,

Try this. It gives you a lot smaller table by packing two bytes into each word space. If you stick with the RETLW approach just uncomment the addwf WREG.

ASM
SineTable   
  movlw UPPER Table1
  movwf TBLPTRU
  movlw HIGH Table1
  movwf TBLPTRH
  movlw LOW Table1
  movwf TBLPTRL
  movf _STEPCOUNT,W
  ;addwf WREG     ; uncomment only if using RETLW tables VS db
  addwf TBLPTRL
  TBLRD*
  movf  TABLAT, W
  return
 
Table1
  db 0,128,148,167,185,200,213,222,228,230,228,222,213,200,185,167
  db 148,128,180,108,89,71,56,43,34,28,26,28,34,43,56,71,89,108
ENDASM

[circuitpro]

I've been trying to use DT_INTS-14 with a 16F877A. I'm getting errors when trying to compile. Code is as follows:

DEFINE    OSC 4

'Define LCD registers and bits
Define  LCD_DREG        PORTD
Define  LCD_DBIT        4
Define  LCD_RSREG       PORTE
Define  LCD_RSBIT       0
Define  LCD_EREG        PORTE
Define  LCD_EBIT        1

'OPTION_REG.6 = 0 
OPTION_REG.7=0                               'ENABLE PORTB PULLUPS
ADCON1 = 7                                   
Low PORTE.2                                  
Pause 100                                    

'INCLUDE FILES FOR DT INTERRUPTS  
INCLUDE "DT_INTS-14.bas"
INCLUDE "ReEnterPBP.bas"

X         VAR  BYTE
Y         VAR  BYTE
Z         VAR  BYTE
COUNTER   VAR  BYTE
TAG       VAR  BYTE[26]

INIT:
'INITIALIZE INTERRUPTS
ASM
INT_LIST  macro   ;IntSource,Label,Type,ResetFlag?
        INT_Handler  RBC_INT,  _BChange, PBP, yes                  
    endm
    INT_CREATE
ENDASM

@ INT_ENABLE RBC_INT

START:
COUNTER=0

MAIN:
IF COUNTER=>26 THEN
     LCDOUT $FE,1,"COUNTER: ",DEC COUNTER
     LCDOUT $FE,$C0,STR TAG\15
     COUNTER=0
ENDIF
GOTO MAIN

BChange:
COUNTER=COUNTER+1
IF PORTB.0=0 THEN
     TAG[COUNTER]=0
ENDIF
IF PORTB.1=0 THEN
     TAG[COUNTER]=1
ENDIF
@ INT_RETURN

The errors I'm getting are:
Error [113] c:(path)pbppic14.lib 1181: Symbol not previously defined (wsave)
Error [101] c:(path)code\lab-x1.asm 194: Error: (wsave variable not found,)
Error [101] c:(path)code\lab-x1.asm 258: Error: (" Add:" wsave VAR BYTE $70 SYSTEM)
Error [101] c:(path)code\lab-x1.asm 315: Error: (Chip has RAM in BANK1, but wsave1 was not found.)
etc
etc

Can somebody tell me what's wrong?

Thanks

[ScaleRobotics]

Yes, it is asking you to change the include file here:

wsave   VAR BYTE    $20     SYSTEM      ' location for W if in bank0
;wsave   VAR BYTE    $70     SYSTEM      ' alternate save location for W 
                                         ' if using $70, comment out wsave1-3

' --- IF any of these three lines cause an error ?? ---------------------------- 
'       Comment them out to fix the problem ----
' -- It depends on which Chip you are using, as to which variables are needed --
wsave1  VAR BYTE    $A0     SYSTEM      ' location for W if in bank1
wsave2  VAR BYTE    $120    SYSTEM      ' location for W if in bank2
wsave3  VAR BYTE    $1A0    SYSTEM      ' location for W if in bank3

It needs to be adjusted for a few different chips. Comment out the wsave at $20, and uncomment the wsave at $70, and try commenting out the wsave1-3.

[circuitpro]

scalerobotics - Thanks very much.

[HankMcSpank]

Just wondering if doing something like this is a 'no no' wrt to the interrupt handlers...

CPM1_Interrupt_Handler:

@ INT_DISABLE  CMP1_INT
[do some stuff here]
@ INT_ENABLE  CMP2_INT

@ INT_RETURN


CPM2_Interrupt_Handler:

@ INT_DISABLE  CMP2_INT
[do some stuff here]
@ INT_ENABLE  CMP1_INT

@ INT_RETURN

....essentially 'toggling' between each comparator being 'interrupt' enabled (& where the other comparator enables/disables itself & its partner). I'm getting weird results, but that's probably cos the rest of my code isn't robust - but just wanted to establish if it's ok to do this (especially if the comparators are interrupting rapidly due to them both rx'ing a rapidly changing input - and also each comparator potentially interrupting very closely in time)

Also, not having a clue about this kinda stuff, just wondering what's going on 'under the hood' so to speak....ie when an interrupt enable &/or disable is actioned as per the above? (does enabling/disabling in such a manner use a lot of processor clock cycles? Or is it pretty swift?)

Thanks.