TAP Controller

JTAG Debugging – TAP Controller

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JTAG Debugging - TAP Controller

Implementing the TAP controller within the SoC, interfacing with the JTAG chip in the JTAG hardware box to receive and process JTAG sequences. Its main structure is as follows:As can be seen, there is a state machine, an Instruction Register (IR), several Data Registers (DR), a Bypass Register, etc.The state machine is controlled by TMS, … Read more

Learning JTAG Standard (IEEE1149.1) – Part 2

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Learning JTAG Standard (IEEE1149.1) - Part 2

TAP controller The TAP controller is a finite state machine that transitions states based on the TMS signal at the rising edge of TCK, generating control signals to operate the JTAG circuit. The state transition diagram of the TAP controller is shown below: Each state is described as follows: Test-Logic-Reset: The test logic is disabled, … Read more