DEBUG APPARATUS AND METHODS FOR DYNAMICALLY SWITCHING POWER DOMAINS

Methods and apparatus are provided that facilitate debugging operations for components in dynamic power domains. In an embodiment, an integrated circuit includes hardware sectors associated with observability circuits served by a debug data bus of a debug circuit. A controlled sector residing in a dynamically-controlled power domain may be turned off while the power domain of another sector remains on. To continue to have debug observability all the way through and after these power events, a debug data register is configured to provide data, such as configuration and/or programming data, to the observability circuit of the controlled sector via the debug data bus. A shadow register is configured to capture the data provided to the controlled sector's observability circuit. The shadow register data is used upon restoring power to the controlled sector to restore the controlled sector's observability circuit to a state when the controlled sector was previously powered on.