zeros are returned this is repeated for dip 190 such that pin 21 is set high for controller 144 to determine the position of switches 1 5 of dip 190 and pin 20 is set high for controller 144 to determine the position of switches 6 10 of dip 190 once all of these settings and readings have been made the receiver 50 is ready to receive a plurality of different codes at a plurality of different frequencies as discussed above the switching from one frequency to another can easily be accomplished by turning on or off a signal diode when on the signal diode adds capacitance to the bandpass filter adjusting the frequency to some lower frequency when the diode is off the signal diode takes out the additional capacitance out of the bandpass filter adjusting the frequency back to the original or some higher frequency additional digital frequency control of a receiver can be achieved by adding signal diodes connected to additional frequency circuitry fig5 a g are flow charts of the software executing in controller 144 the main routine 200 of the software initializes the controller settings and will only be performed at the initial startup of the controller 144 in.