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Heartbeat LED
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A very nice illumination effect is the Heratbeat effect. The following Software enables an Atmel Controller (typically Tiny12) to pulsate LED's connected to it. This is a really hypnotizing effect, suited well for case Modding and RC Model DIY. Maybe you want to illuminate your CPU with this Eyecatcher!
You could use this this circuit circuit to obtain a very small PCB that can be used nearly everywhere.
To download the Source Code, follow this link.
The Program is very straightforward, but some of the techniques shown can be ust in larger projects.
Reading of the EEPROM
Timer-Interrupt
Software-Counter
The Main Loop only generates a Software PWM Signal.
The Timer Interrupt changes the brightnes between a minimum and a maximum, with different speed, creating a very realistic Heartbeat effect!
Program developed with AVR Studio 4.10.
When programming, store the OSCCAL-Value in EEPROM-Cell $3f !
;Hearbeat LED
;(C) 2004 Markus Vohburger
;Gewerbliche Nutzung untersagt.
;
;Registerdefinitionen für Tiny12 ladan
.include "tn12def.inc"
.def temp1 = r16
.def temp2 = r17
.def output = r18
;Software-Zähler
.def swcount = r19
.def output = r20
;Zähler für PWM
.def pwmcount = r21
;Richtung heller oder dunkler
.def direction = r25
;Wert für PWM
.def pwmvalue = r27
;Kalibrierbyte für internen Oszillator ist in EEPROM $3f gespeichert
.equ EE_OSCCAL= $3f;
;reset-Vektor
.org $0000
rjmp main
;Timer 0 Overflow Interrupt Vektor
;timer overflow interrut handler
.org OVF0Addr
rjmp OVF0Handler
;Hauptprogramm beginnt hier
.org $0010
main:
;set internal osc cal
ldi temp1,EE_OSCCAL
rcall readeeprom
out osccal,temp1
;Ports Setup
ldi temp1,$1f
out ddrb,temp1
ldi temp1,$1f
out portb,temp1
clr pwmcount
clr pwmvalue
clr direction
;Timer zurücksetzen
clr temp1
out tcnt0,temp1
;Timer interrupts an
ldi temp1,(1<<toie0)
out timsk,temp1
;Timer starten
ldi temp1,$02
out tccr0,temp1
ldi swcount,0
sei
;hauptschleife, implementiert die PWM
loop:
;leds aus
ldi output,$1f
check_value:
cp pwmvalue,pwmcount
brsh writeoutput
;leds an (PB0 bis PB2)
andi output,$18
writeoutput:
out portb,output
inc pwmcount
rjmp loop
;subroutine zum Lesen aus EEprom
readeeprom:
sbic eecr,eewe
rjmp readeeprom
out eear,temp1
in temp1,eedr
ret
;Timer 0 Interrupthandler
OVF0Handler:
;statusregister sichern
in r1,sreg
;Softwarezähler erhöhen
inc swcount
cpi swcount,$04
brlo exit_ovf0handler
clr swcount
cpi direction,$00
breq dodec
;pwmwert erhöhen
doinc:
inc pwmvalue
cpi pwmvalue,$80
brlo exit_ovf0handler
clr direction
ldi pwmvalue,$80
rjmp exit_ovf0handler
;pwmwert verringern
;das Verringern geschieht doppelt so schnell wie das Erhöhen, um den Effekt zu verbessern
dodec:
dec pwmvalue
dec pwmvalue
cpi pwmvalue,$01
brsh exit_ovf0handler
ldi pwmvalue,$01
ldi direction,$01
;ende der Timer 0 Interrupt Routine
exit_ovf0Handler:
out sreg,r1
reti
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