Abstract: A circuit for encoding and decoding key input data from a matrix of switches with a single transmission wire. The circuit for encoding and decoding key input data with a single transmission wire includes a control circuit, a charge storage circuit and a keyboard matrix circuit. The keyboard matrix circuit is composed of a group of resistors connected in series. Each resistor is coupled to ground via a manually actuated switch. When one of the switches is actuated or closed the switch provides an electrical path to ground through the resistors that precede the switch and shorts the resistors that follow the switch. When one of the switches is closed the charge stored on the charge storage circuit dissipates through the electrical path to ground provided by the actuated switch, at a rate related to the sum of the resistance preceding the switch.

Abstract: The remote control comprises a microprocessor including a CPU and memory, a keypad including keys for operating the remote control coupled to the microprocessor, signal outputting circuitry, driver circuitry coupled to the microprocessor for driving the signal outputting circuitry, hardware and software, including the microprocessor, for generating output signal data which is supplied to the driver circuitry, a signal coupling transducer, such as a pick-up coil, in the remote control for picking up electro-magnetic signals from an electro-magnetic signal emitting or transmitting device, such as a telephone handset, coupling circuitry for coupling the signal coupling transducer to the microprocessor and decoding software in the microprocessor for decoding the electro-magnetic signals picked up into bits and/or bytes of output signal data and storing same in the memory.