Systems and methods for monitoring integrated circuit internal states

A system for monitoring internal states of an integrated circuit, comprising:

• logic nodes disposed within the integrated circuit;
• selection logic coupled to monitor pins externally accessible on the integrated circuit, the selection logic configured to retrieve internal states of select logic nodes based on signals applied via the monitor pins that identify the select logic nodes, wherein the selection logic comprises n cascaded multiplexers, wherein n−1 of the n cascaded multiplexers have as an input an output of a previous multiplexer in the cascade, wherein n is greater than or equal to three;
• and
• a monitor unit configured to apply the signals to the monitor pins and to read the internal states of the select logic nodes via the monitor pins.

A method of monitoring internal states of an integrated circuit, comprising:

• receiving logic select signals that identify one or more logic nodes of the integrated circuit from a monitoring unit via a first portion of pins on an external surface of the integrated circuit;
• multiplexing, via n cascaded multiplexers, internal states from the one or more logic nodes to one or more output lines based on the received logic select signals, wherein n−1 of the n cascaded multiplexers have as an input an output of a previous multiplexer in the cascade and wherein n is greater than or equal to three;
• and
• coupling the multiplexed internal states to a second portion of the pins for monitoring by the monitoring unit.

A system for monitoring logic elements within an integrated circuit, comprising:

• a plurality of logic elements within the integrated circuit;
• a plurality of cascaded multiplexers coupled to the plurality of logic elements;
• selection logic coupled to monitor pins externally accessible on the integrated circuit, the selection logic comprising the plurality of cascaded multiplexers coupled to the plurality of logic elements, the plurality of cascaded multiplexers configured to:
• identify a specific logic element from the plurality of logic elements based on signals applied via the monitor pins, and
• multiplex an input signal to, or output signal from, the specific logic element to the monitor pins.

A method of monitoring internal states of an integrated circuit, comprising:

• providing selection logic within the integrated circuit, wherein the selection logic is connected to pins externally accessible on the integrated circuit and wherein the selection logic comprises a plurality of multiplexers;
• applying signals to the selection logic, via a first portion of the pins, that identify one or more nodes of the integrated circuit to be selected;
• and
• reading an internal state of the one or more selected nodes via a second portion of the pins.