I was looking for help with this on another thread but I didn't get responses so I figured I'd create another around this. I'm trying to add a simple 8X1 table that adds spark based on the commanded AFR to my modified version of $6E. For some reason the code I wrote doesn't work. I've tried various code changes but nothing seemed to help. I output the converted AFR value in a datalog to see if it was actually doing anything and it just gives me a blank (00) value, so either the code isn't being run for some reason or I must not be handling the AFR value (L00D5) properly. All the start up spark code has been removed. This is what I wrote.


CE FF FF DC D5 02 C1 B8 23 02 86 B8 C6 48 CE C1 9D BD F3 F2 97 12


;-------------------------------------------------
;
; Lk Up Spark vs Commanded AFR Tbl
;
;-------------------------------------------------
F853: LDX #65535 ; LOAD 16B TO 8B CONV #
F856: LDD L00D5 ; COMMANDED AFR
F858: IDIV ; CONV TO TABLE UNITS

F859: CMPB #184 ; COMP TO MAX AFR FOR LK UP
F85B: BLS LF85F ; BR IF AFR LOWER
; ... else
F85D: LDAA #184 ; Force MAX AFR FOR LOOK UP
F85F: LDAB #72 ; MIN AFR FOR LK UP
F861: LDX #$C19D ; INDEX HWY MODE SPARK TBL
F864: JSR LF3F2 ; 2D lk up, W/MIN VAL

F867: STAA L0012 ; SAVE AFR SPARK ADVANCE

 

There is a simple error in the high limit check. You are testing reg B, but then load reg A if the value is too high. Then reg B gets the table low offset parameter.

To go from the internal FAR value to an AFR value, need to reconstruct the IDIV. Note how IDIV works:

Operation: (ACCD)/(IX); IX: Quotient, ACCD: Remainder

LDD #65535 ; conversion constant
LDX L00D5 ; COMMANDED FAR
IDIV ; CONV TO TABLE UNITS

At this point the LSB of IX holds the AFR (times 10).

RBob.

 

Didn't notice that, thanks . Any idea as to why it returns 00 when I output it to datalog after the IDIV operation?


Edit- I may have answered my own question. Testing...