It keeps running in the background. The interrupts will not wait for PBP statements to finish.
Ok fine, ... for many years I've resisted making a count down elapsed timer for humanitarian reasons. But if you guys are going to do it anyhow, I might as well make a new version of the Elapsed Timer. I can only hope that if somebody uses it for nefarious purposes, they end up blowing themselves up.
Here's the test circuit.
Here's the test program ...
' Define LCD connections
DEFINE LCD_DREG PORTC ' Set LCD Data port
DEFINE LCD_DBIT 4 ' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_RSREG PORTC ' Set LCD Register Select port
DEFINE LCD_RSBIT 2 ' Set LCD Register Select bit
DEFINE LCD_EREG PORTC ' Set LCD Enable port
DEFINE LCD_EBIT 3 ' Set LCD Enable bit
DEFINE LCD_BITS 4 ' Set LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 2 ' Set number of lines on LCD
DEFINE LCD_COMMANDUS 2000 'Command delay time in us
DEFINE LCD_DATAUS 50 'Data delay time in us
DEFINE OSC 4
INCLUDE "Elapsed_DN.bas" ; Elapsed Timer Routines
ZERO_LED VAR PORTB.3
ANSEL = 0 ' All Digital
ANSELH = 0
LOW ZERO_LED ' start with LED OFF
OPTION_REG.7 = 0 ' enable PORTB pull-ups
PAUSE 250
LCDOUT $FE,1 ' Initialize LCD
PAUSE 250
Days = 1 ' set initial time
Hours = 1
Minutes = 3
Seconds = 10
GOSUB StartTimer ' Start the Elapsed Timer
Main:
CountDown = !PORTB.0
IF SecondsChanged = 1 THEN
SecondsChanged = 0
LCDOUT $FE,2, DEC Days,"d-",DEC2 Hours,":",DEC2 Minutes,":",DEC2 Seconds
ENDIF
IF ZERO_LED != ZERO THEN ZERO_LED = ZERO
GOTO Main
If the button on PORTB.0 is pressed it counts down. If it is not pressed, it counts up. The LED comes on when it reaches 0.
If you are using the countdown for a movie set, it has to stop at 1 second. Put this in the main loop.
IF (CountDown=1) AND (Days=0) AND (Hours=0) AND (Minutes=0) and (Seconds=1) _
THEN GOSUB StopTimer
You'll need the ASM_INTS include from the original Elapsed Demo.
Page last modified on February 21, 2018, at 10:41 AM