For an embedded core, which is deeply embedded in the system chip, direct physical access to its peripheries is not available by default;hence, additional access mechanisms are required.

• 由于嵌入核与芯片的输入／输出管脚没有直接通路，因此需要设计专门的测试通路结构对它们进行测试，以减少测试时间，降低测试成本。