JTAG Test Port

13

This chapter presents the theory of operation information about the 21555 JTAG interface. See Chapter 16 for specific information about the JTAG registers.

The 21555’s implementation of the JTAG test port is according to IEEE Std. 1149.1, IEEE Standard Test Access Port and Boundary-Scan Architecture.

The JTAG test port consists of the following:

•A 5-signal test port interface.

•A test access port controller.

•An instruction register.

•A bypass register.

•A boundary-scan register.

13.1JTAG Signals

The JTAG test access port is to be used only while the 21555 is not operating. Table 30 describes JTAG signals.

Table 30. JTAG Signals

Signal

Type

Description

Name

 

 

 

 

 

tck

I

JTAG boundary-scan clock. Signal tck is the JTAG logic control clock. This pin has an internal weak pull-down

resistor.

 

 

 

 

 

 

 

JTAG serial data in. Signal tdi is the serial input through which JTAG instructions and test data enter the JTAG

tdi

I

interface. The new data on tdi is sampled on the rising edge of tck. An unterminated tdi is pulled high by a

 

 

weak pull-up resistor internal to the device.

 

 

 

tdo

O

JTAG serial data out. Signal tdo is the serial output through which test instructions and data from the test logic

leave the 21555.

 

 

 

 

 

 

 

The JTAG test mode select pin, tms causes state transitions in the Test Access Port (TAP) controller. The tms

tms

I

signal is pulled high by a weak pull-up resistor internal to the device. If this pin is low while t_rst_l is low the

device can enter an unsupported mode. Other devices that are not on early power and are connected to the

 

 

JTAG Scan Chain, pull tms low during Hot Insertion causing the 21555 to enter the unsupported mode.

 

 

During the Hot Insertion isolate this signal from other JTAG devices on the circuit board or JTAG scan chain.

 

 

 

 

 

JTAG TAP reset and disable. When low, JTAG is disabled and the TAP controller is asynchronously forced

 

 

into the reset state, which in turn asynchronously initializes other test logic. An unterminated trst_l is pulled

trst_l

I

high by a weak pull-up resistor internal to the device. The TAP controller must be reset before the JTAG

 

 

circuits can function. For normal JTAG TAP port operation, this signal must be high.

 

 

Prior to normal 21555 operation, this signal must be strobed low or pulled low with a 1kΩ resistor.

 

 

 

21555 Non-Transparent PCI-to-PCI Bridge User Manual

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Intel 21555 user manual Jtag Test Port, Jtag Signals
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21555 specifications

The Intel 21555 is a prominent microprocessor developed by Intel, designed to cater to a variety of computing needs. This processor marks a significant step forward in Intel's lineup and underscores the company's commitment to advancing technology in personal computing, enterprise solutions, and beyond.

One of the standout features of the Intel 21555 is its advanced architecture. It utilizes a multi-core design, enabling improved performance through parallel processing. This architecture allows multiple applications to run seamlessly without a decline in speed. The cores are built on a cutting-edge manufacturing process that enhances energy efficiency while maintaining high clock speeds.

The Intel 21555 supports a wide range of technologies, including Intel Turbo Boost, which enables dynamic adjustments to the processor’s performance based on workload demands. This feature allows the processor to accelerate its speed during intensive tasks, providing users with a responsive experience when it matters the most.

Another key characteristic of the Intel 21555 is its support for integrated graphics. With Intel UHD Graphics technology, users can enjoy enhanced visuals for everyday tasks such as video playback, web browsing, and light gaming. This eliminates the need for a separate graphics card for many users, particularly in home office or light gaming scenarios.

Security is a significant focus in the design of the Intel 21555. It includes built-in hardware-based security features like Intel Trusted Execution Technology and Secure Boot. These features help protect against various types of threats, ensuring that user data remains secure from malicious attacks.

The Intel 21555 is also optimized for use with Intel's platform technologies, including Intel Optane memory and Intel Rapid Storage Technology. These technologies work together to deliver faster boot times and improved system responsiveness, making computing more efficient for users.

Furthermore, the Intel 21555 is designed to support virtualization technologies, allowing multiple operating systems to run concurrently without compromising performance. This is particularly useful for developers and businesses that rely on virtualization for testing and development environments.

In summary, the Intel 21555 is a powerful and versatile processor that reflects Intel's ongoing innovation in the computing space. With its multi-core architecture, enhanced graphics capabilities, strong security features, and advanced technologies, it stands out as an excellent choice for a wide range of applications, serving both casual users and professionals alike.
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