Microprocessor oriented configurable logic element

Abstract

A microprocessor controlled configurable logic circuit achieves versatility by including a configurable combinational logic element, a configurable storage circuit, a configurable status buffer, and a configurable output select logic. The input signals to the configurable combinational logic element are input signals to the configurable logic circuit and feedback signals from the storage circuit. The storage circuit may be configured to operate as a D flip-flop with or without set and reset inputs, or as an edge detector. In conjunction with the combinational logic element, the storage circuit may also operate as a stage of a shift register or counter. The output select logic selects output from among the output signals of the combinational logic element and the storage circuit. The configurable status buffer may be configured to provide status information on selected important internal signals of the configurable logic circuit. A microprocessor interface structure may access an array of these configurable logic circuits through the status buffer to read different internal output signals from different circuits in the array. Providing separate input and output to a microprocessor leaves the storage element free for other uses and does not require the logic provided by the logic elements.