Abstract: A circuit (100) in which two I.C.'s (102, 104) are under control of a single microcontroller that issues operating commands to the two I.C.'s via shared communication lines, including a clock line, a serial data line, and a chip enable line. The two I.C.'s use differing communication protocols. For example, a first I.C. uses a common shift register protocol and has a serial data output while a second I.C. uses a C2B communication protocol. The chip enable line provides chip enable signal pulses (120) that are suitable for the chip enable input of the second I.C. (104). An interface circuit (106) on the same board that contains the two I.C.'s, interfaces the chip enable line to a strobe input of the first I.C. (102) to create strobe signal pulses suitable for the protocol of the first I.C. (102). The interface circuit performs timing and voltage limiting functions. Data enters the second I.C. only after having been clocked through the first I.C.

Abstract: A diagnostic system for detecting when one or more temperature sensors as found in motor vehicle climate control systems are invalid. The system works at extreme temperature conditions and functions to distinguish between sensor faults such as open or short circuits and true sensor temperature readings, which could be, misinterpreted as faulty readings. In particular, combinations of ambient temperature sensors, in-car-temperature sensors and evaporator air temperature sensors are tested by the diagnostic algorithm to make such determinations.

Abstract: A method and system for controlling a heating, ventilation and air-conditioning (HVAC) system of a vehicle to prevent fogging of a windshield of the automotive vehicle is provided. The method and system include a determination of whether the vehicle has been recently turned "off", and upon determining the vehicle has been recently turned "off", commanding the HVAC system to a floor mode.

Abstract: In one embodiment of the present invention, across an electrical load to prevent over dissipation semiconductor switch in the event of a short circuit. The system includes a microprocessor with a terminal which is alternatively configurable as an input and as an output. When the terminal is configured as an output, the microprocessor can turn the electrical load ON and OFF via a transistor, under software control. Once the microprocessor turns the load ON, the microprocessor reconfigures its terminal to be an input. The system automatically latches the electrical load ON until a short circuit occurs or until the microprocessor turns the load OFF. When a short circuit occurs, the system automatically turns the load OFF. With the microprocessor terminal configured as an input, the microprocessor can detect when the system has automatically turned the load OFF due to a short circuit, thus being able to set a diagnostic code or take other appropriate action.