;***** main loop **********************
;===== sensor OFF: LED_green blink
LED_Blnk:
　 wdr ;reset watch_dog timer
　 sbi PInB,_LED_Gr ;toggle LED_green ON/OFF
　 ldi YH,HIGH(1000) ;delay for 1Sec
　 ldi YL,LOW(1000)
;
LED_Blnk1: ;delay for 1mS
　 ldi ZH,HIGH(1989) ;adjusted by oscilloscope
　 ldi ZL,LOW(1989)
LED_Blnk2:
　 sbiw ZL,1 ;1mS elapsed ?
　 brne LED_Blnk2 ;No, wait 1mS
;
　 sbis ACSR,_ACO ;Yes, then comparator is Hi (sensor is OFF) ?
　 rjmp OSC_Out ; No, goto output OSC wave
　 sbiw YL,1 ; Yes, then 1S elapsed ?
　 brne LED_Blnk1 ; No, wait 1S
　 rjmp LED_Blnk ; Yes, loop again
;
;===== sensor ON: OSC output
OSC_Out:
　 sbi PortB,_LED_Gr ;LED_green turn OFF
　 cbi PortB,_LED_Rd ;LED_red turn ON ;
OSC_HL:
　 wdr ;reset watch_dog timer
　 sbi PortB,_AMP ;OSC High period (speaker ON)
　 ldi YL,Hi_period
OSC_H:
　 subi YL,1
　 brne OSC_H
;
　 cbi PortB,_AMP ;OSC Low period (speaker OFF)
　 ldi YL,Lo_period
OSC_L:
　 subi YL,1
　 brne OSC_L
　 sbis ACSR,_ACO ;comparator is Hi (sensor is OFF) ?
　 rjmp OSC_HL ;No, OSC go on
;
　 sbi PortB,_LED_Rd ;Yes, LED_red turn OFF
　 rjmp LED_Blnk ;return to LED_green blink
;