Abstract: An environment monitoring integrated circuit is provided that allows the boundaries of operating parameters to be conveniently modified. The present invention allows the hardware designer to easily change the temperature boundary of the computer operation, or the boundaries of the operating voltage, the operating temperature and the rotation speed of the fan. The present invention uses limit registers which provide a simple implementation for changing the boundaries of the operating parameters of the computer.

Abstract: A photocoupling signal detection circuit for a computer mouse to simplify the design of circuit by tracking the slope change of input voltage waveform and produce a digital output which can detect the movement of computer mouse is disclosed. This signal detection circuit includes a comparator, a state decision circuit, an up/down counter, and a D/A converter. The comparator produces an up/down signal connected to the state decision circuit, then the up/down signal connected to the up/down counter to transfer the up/down signal into a digital signal output. The digital signal connected to a D/A converter for transferring into an analog signal, and the analog signal can be compared with the output signal of an phototransistor. According to the state of up/down signal, the state decision circuit determines if the phototransistor is turned on or turned off and outputs different state signals, based on its determination. The output state signal is further utilized for the detection of a computer mouse.

Abstract: An IEEE Std. 1149.1 boundary scan circuit which is capable of performing built-in self-testing includes a logic circuit, cascaded input boundary-scan cells that form an input boundary-scan register connected to input nodes of the logic circuit, cascaded output boundary-scan cells that form an output boundary-scan register connected to output nodes of the logic circuit, and a test access port system for controlling operation of the input and output boundary-scan cells. The test access port system provides a built-in self-test control signal to the input and output boundary-scan cells when executing built-in self-testing. The input boundary-scan register is reconfigurable to operate as a test pattern generator that provides test patterns to the logic circuit for a predetermined number of clock cycles upon receipt of the built-in self-test control signal.