Counting time via external pulses

[mackrackit]

Pseudo code.

IF PULSE THEN
SEC = SEC + 1

IF SEC = 60 THEN
SEC = 0
MIN = 1
...

[Marin]

I did that, now my main problem is counting backwards......problem is if I count backward evrytime secounds passes 59 to 00 minute raises for 1, same happend if I go backward, but if should decrese

this is my code:

loop1:
if porta.1=0 then
counter=counter+1
if counter == 12 then
sekunda = sekunda +1
counter = 0
endif
if sekunda == 60 then
minuta = minuta +1
sekunda = 0
endif
IF minuta == 60 then
sat = sat +1
minuta =0
endif

goto lcd
endif

if porta.0=0 then
if counter == 0 then
counter = 12
if sekunda == 0 then
sekunda = 60
endif
sekunda = sekunda -1
endif
counter=counter-1
goto lcd
endif

goto loop1

lcd:

lcdout $fe,$c0,dec2 counter,"TCR:",DEC2 sat,":", dec2 minuta,":",dec2 sekunda
while (porta.0=0 or porta.1=0)ause 10:wend
goto loop1