In-circuit emulator with gatekeeper for watchdog timer
First Claim
1. An In-Circuit Emulation system, comprising:
- a microcontroller having a microcontroller clock;
a virtual microcontroller running in lock-step synchronization with the microcontroller;
a host computer running In-Circuit Emulation debug software, the host computer being in communication with the virtual microcontroller; and
a gatekeeper circuit coupled to the virtual microcontroller and the microcontroller, the gatekeeper circuit detecting when a watchdog timer expires in the microcontroller and notifying the host computer that the watchdog event has occurred, wherein the gatekeeper circuit further comprises switching means for replacing the microcontroller clock signal with the gatekeeper clock signal for clocking the virtual microcontroller when a watchdog event occurs; and
a gatekeeper clock running independent of the microcontroller clock to clock operations carried out in the gatekeeper circuit.
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Accused Products
Abstract
A watchdog timer control using a gatekeeper in an In-Circuit Emulation system. The In-Circuit Emulation system has a microcontroller operating in lock-step synchronization with a virtual microcontroller. When a watchdog event occurs, the gatekeeper, forming a part of the virtual microcontroller, crowbars the reset line of the virtual microcontroller as well as the real microcontroller. This freezes the state of the virtual microcontroller so that debug operations can be carried out. The gatekeeper operates with its own gatekeeper clock independent of the microcontroller clock. When a watchdog event occurs, the gatekeeper clock is rerouted to the virtual microcontroller to facilitate debug operations of the virtual microcontroller.
83 Citations
13 Claims
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1. An In-Circuit Emulation system, comprising:
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a microcontroller having a microcontroller clock; a virtual microcontroller running in lock-step synchronization with the microcontroller; a host computer running In-Circuit Emulation debug software, the host computer being in communication with the virtual microcontroller; and a gatekeeper circuit coupled to the virtual microcontroller and the microcontroller, the gatekeeper circuit detecting when a watchdog timer expires in the microcontroller and notifying the host computer that the watchdog event has occurred, wherein the gatekeeper circuit further comprises switching means for replacing the microcontroller clock signal with the gatekeeper clock signal for clocking the virtual microcontroller when a watchdog event occurs; and a gatekeeper clock running independent of the microcontroller clock to clock operations carried out in the gatekeeper circuit. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of processing a watchdog timer event using a gatekeeper circuit, comprising:
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determining that a watchdog timer event has occurred in a microcontroller, the microcontroller running in lock-step synchronization with a virtual microcontroller; asserting a reset in the microcontroller and by holding the reset line of the microcontroller in an asserted state; providing a gatekeeper clock signal to the virtual microcontroller in place of a microcontroller clock signal, wherein the gatekeeper clock runs independently of the microcontroller clock to clock operations carried out in the gatekeeper circuit; notifying a host computer running In-Circuit Emulation software that a watchdog timer event has occurred; and permitting the host computer to query memory locations and registers of the virtual microcontroller. - View Dependent Claims (8, 9)
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10. A method of processing a watchdog timer event using a gatekeeper circuit, comprising:
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determining that a watchdog timer event has occurred in a microcontroller, the microcontroller running in lock-step synchronization with a virtual microcontroller; asserting a reset in the microcontroller and by holding the reset line of the microcontroller in an asserted state; switching a microcontroller clock signal from the virtual microcontroller and replacing the microcontroller clock signal with a gatekeeper clock signal to the virtual microcontroller, wherein the gatekeeper clock runs independently of the microcontroller clock to clock operations carried out in the gatekeeper circuit; and notifying a host computer running In-Circuit Emulation software that a watchdog timer event has occurred. - View Dependent Claims (11, 12, 13)
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Specification