easy6502_heartbeat-blue.asm

; A: Timer, X: Heart color, Y: Color counter
 LDY #$ff  ; Pulse offset
 STY $0010
 LDX #$06   ; Color 1
 STX $0001
 LDX #$0e   ; Color 2
 STX $0002
 LDX #$03   ; Color 3
 STX $0003  
 LDX #$01   ; Color 4
 STX $0004 
 LDX #$0b   ; Color 0
 STX $0000

draw: 
 STX $03ce
 STX $03d0
 STX $03ed
 STX $03ee
 STX $03ef
 STX $03f0
 STX $03f1
 STX $040e
 STX $040f
 STX $0410
 STX $042f

wait:
 ADC #$01
 BCC wait   ; Exercise objective

 INY
 CPY #$00
 BEQ y00
 CPY #$03
 BEQ y03
 CPY #$04
 BEQ y04
 CPY #$06
 BEQ y06
 CPY #$08
 BEQ y08
 CPY #$0a
 BEQ y0a
 CPY #$0c
 BEQ y0c
 CPY #$0e
 BEQ y0e
 CPY #$11
 BEQ y11
 JMP wait   ; Wait more

;Set next colors
y00:
 LDX $0000 
 JMP draw
y03:
 LDX $0001 
 JMP draw
y04:
 LDX $0002 
 JMP draw
y06:
 LDX $0003 
 JMP draw
y08:
 LDX $0004 
 JMP draw
y0a:
 LDX $0003 
 JMP draw
y0c:
 LDX $0002 
 JMP draw
y0e:
 LDX $0001 
 JMP draw
y11:
 LDX $0000
 LDY $0010   ; Re-init color counter
 JMP draw