Processing unit for generating signals for communication with a test access port

An interface circuit comprising:

• a receiver circuit for receiving instructions over a first interface, said first interface for communicating with a general purpose host computer system, said general purpose host computer system generating said instructions in a predetermined data compressed format;
• a control circuit for decoding said instructions and responsive thereto for generating TCK, TDI, and TMS signals for transmission over a second interface and for receiving second signals from said second interface, said control circuit comprising:
• a TCK generator circuit coupled to an instruction data bus and coupled to receive first control signals for generating said TCK signals over said second interface in response to decoded first and second instructions;
• a TDI generator circuit coupled to said instruction data bus and coupled to receive second control signals for generating said TDI signals over said second interface in response to said first instructions;
• and
• a TMS generator circuit coupled to said instruction data bus and coupled to receive third control signals for generating said TMS signals over said second interface in response to said second instructions;
• and
• wherein said second interface and said first and said second signals are for communicating with an access port of a programmable integrated circuit device and conform to the IEEE 1149.1 communication standard.

A communication system comprising:

• a) a general purpose host computer system for translating information stored in a first format to a compressed format, said compressed format comprising a set of instructions;
• b) a hardware unit comprising:
• a receiver circuit for receiving instructions of said compressed format over a first interface, said first interface coupled to said general purpose host computer system;
• and
• a control circuit for decoding said instructions and responsive thereto for generating first signals for transmission over a second interface and for receiving second signals from said second interface;
• and
• wherein said second interface and said first and said second signals conform to a JTAG communication interface;
• and
• c) a programmable integrated circuit comprising an access port, wherein said second interface is for interfacing for communication with said access port.

In a communication system, a method of loading configuration information into a programmable integrated circuit, said method comprising the steps of:

• translating configuration information stored in a first format to a compressed format, said compressed format comprising a set of instructions, said step of translating performed using a general purpose host computer system;
• receiving instructions of said compressed format over a first interface that is coupled to said general purpose host computer system and a hardware unit, said step of receiving performed by said hardware unit;
• decoding said instructions received by said receiver circuit and responsive thereto generating first signals for transmission over a second interface;
• receiving second signals from said second interface and storing said second signals, said above steps of decoding, generating, receiving and storing performed by said hardware unit;
• and
• wherein said second interface and said first and said second signals conform to a JTAG communication interface and wherein further said second interface is for communicating with an access port of a programmable integrated device coupled to said hardware unit.