| 摘要 |
A system and method for communicating with an integrated circuit is provided that allows an integrated circuit to communicate debugging information and system bus transaction information with an external system. The system may include an interface protocol that provides flow control between the integrated circuit and the external system. The system may include a high-speed link and/or a JTAG link for communicating information. A link may be automatically selected by a debug circuit, or selected by an on-chip device or external system. The high-speed link enables real-time collection of trace information. Links may be memory-mapped, such that on-chip devices and other devices attached to the system bus may access the external system. The high-speed link may also operate at a rate which is integrally coupled with a rate of the processor or system bus. Further, the high-speed link may be adapted to change speeds in response to a change in operating speed of the system bus or processor. The JTAG interface may utilize standard JTAG components and instructions such that external devices such as debug adaptors adopting these components and instructions may be re-used for different integrated circuit types. Information transmitted over the JTAG or high-speed link may be compressed to optimize available bandwidth of the links. Also, processor control signals can be transferred through links that allow an external system to manipulate and monitor operation of the processor and its associated modules.
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