Patent Number: 6,307,464

Title: Method and apparatus using phases for communication in thermostat circuit

Abstract: In a receiver circuit module (22) having a microcontroller (U1), an output line (FILTER_LED) connectable to a source circuit module (20) is also used as an input. A switch (SW2) disposed in the source circuit module is closed to change the wave form which is read by the microcontroller as an input signal to drive a 5V signal to the gate of a solid state switch (Q1) turning it on to thereby energize an output device in the source circuit module via the same output line (FILTER_LED). By means of the dual function of the output line the control can notify a user of an HVAC system, for example, of system problems with a blinking light and/or an audible alarm as well as serving to notify the user at a remote location that selected maintenance is due, such as a need to change filters without additional control lines. The source circuit module can be mounted near the thermostat of the HVAC system or on the central heating and cooling unit.

Inventors: Miller; Mark E. (Versailles, KY), Anderson; Timothy L. (Lexington, KY), Garnett; Ronald E. (Lexington, KY)

Assignee: Texas Instruments Incorporated

International Classification: F24F 11/00 (20060101); H04M 011/04 ()

Expiration Date: 10/23/2018