Refining the Odyssey 2 Battery Monitor Program
Topic:
Batteries Posted:2004-05-09
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In this article I wrote a voltage monitor for the battery hooked up to my PV system that
runs on an Odyssey 2 computer. Well, it was not the most efficient; however it did work fine. Here is a modification
of the program:
cpu 8048 ; asl needs this to know how to assemble
org 0410h ; start of ROM, but bypass interrupts, etc.
start call 00f1h ; BIOS reset
call 011ch ; BIOS display off
mov r0,#10h ; starting character pointer for VDC
mov r2,#01h ; 02 characters
mov r3,#28h ; x position
mov r4,#70h ; y position
mov r6,#03h ; color start with grey
mov r1,#00h
mov a,#0ffh ; location of memory mapped input
movp a,@a
add a,#58h ; a is 0 at 10.06 volts
mov r7,a
inc r7 ; r7 will dec once before loop
clr a ; start a at 0
clr c ; start with no carry set
vstep add a,#06h
da a
jc wrap
vstepi djnz r7,vstep
jmp disp
wrap inc r1
jmp vstepi
disp mov r7,a
mov r5,#01h ; always tens place =1
call 03eah ; print character BIOS routine
mov a,r1
mov r5,a
call 03eah ; print character BIOS routine
mov r5,#27h
call 03eah ; print character BIOS routine
mov a,r7
swap a
anl a,#0fh
mov r5,a
call 03eah ; print character BIOS routine
mov a,r7
anl a,#0fh
mov r5,a
call 03eah ; print character BIOS routine
mov r5,#0ch
call 03eah ; print character BIOS routine
mov r5,#24h
call 03eah ; print character BIOS routine
mov r5,#17h
call 03eah ; print character BIOS routine
mov r5,#0Eh
call 03eah ; print character BIOS routine
mov r5,#14h
call 03eah ; print character BIOS routine
mov r5,#19h
call 03eah ; print character BIOS routine
call 0127h
mov r1,#0ffh
lpo mov r7,#0ffh
lpi djnz r7,lpi
djnz r1,lpo
call 011ch ; BIOS display off
jmp start
org 04ffh ; these are not read when live
db 0a8h ; 10.06 they are just used when
; db 0b7h ; 10.96 using the emulator to
; db 0b8h ; 11.02 test
; db 0d9h ; 13.00
I used the Decimal Adjust Accumulator command to do some BCD math. To test some of the values, I modified the
gendat.pl code:
$i=10;
$c=167;
while($i<14.6){
printf "%i %2.2f\n",$c,$i;
$i=$i+.06;
$c++;
}
This will list the decimal values for various voltages on my PV system:
divine@trasho o2 $ perl gendatm.pl
167 10.00
168 10.06
169 10.12
170 10.18
171 10.24
172 10.30
.
.
.
240 14.38
241 14.44
242 14.50
243 14.56
divine@trasho o2 $
Here is the binary for the ROM image. I hope you enjoy this new version as much as I did.
I would like to say that one important point about technology reuse is that the mental concentration needed to make
code efficient on an old microcontroller like this is like nothing else. You really have to think clearly to make
this stuff work. Nothing is hidden. I remember working on my homebrew computer
back in 1990 and realizing this as well. At the time, this was programming binary into a front panel to get the homebrew
to talk to my laptop via the parallel port. It was exhilarating. I felt like I was cranking through a single roll of paper,
pure, screaming, bits on, bits off, flashing, looping, buzzing through the ALU of the Z-80. :-)