Code:
Lights var PortB.1
LightStatus VAR BYTE
SYMBOL WStatus = LightStatus.0
ChkLights var bit

  
WStatus = 0
ChkLights = lights   ' Take status.

IF RTCHour = SetlightOnHour THEN
     IF RTCMin = SetlightOnMin THEN
        Lights = 1
        WStatus = 1   ' set flag for write.
     ENDIF
ENDIF

IF RTCHour = SetlightOffHour THEN
    IF RTCMin = SetlightOffMin THEN
       Lights = 0
       WStatus = 1   ' set flag for write.
    ENDIF
ENDIF

if WStatus = 1 then                 ' Flag is set
    if chklights <> lights then     ' and lights pin changed its status; so write.
        WRITE 95, Lights            ' This way, writing to eeprom for entire 1 minute duration is avoided.
        WStatus = 0        ' clear flag. 
    endif
endif