SCANPSC110FSC 데이터 시트보기 (PDF) - Fairchild Semiconductor

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SCANPSC110FSC

SCAN Bridge Hierarchical and Multidrop Addressable JTAG Port (IEEE1149.1 System Test Support)

Fairchild Semiconductor 

Overview of SCANPSC110F Bridge Functions

FIGURE 1. SCANPSC110F Bridge Architecture

SCANPSC110F BRIDGE ARCHITECTURE

Figure 1 shows the basic architecture of the

SCANPSC110F. The device’s major functional blocks are

illustrated here. The TAP Controller, a 16-state state

machine, is the central control for the device. The instruc-

tion register and various test data registers can be scanned

to exercise the various functions of the SCANPSC110F

(these registers behave as defined in IEEE Std. 1149.1).

The SCANPSC110F selection controller provides the func-

tionality that allows the 1149.1 protocol to be used in a

multi-drop environment. It primarily compares the address

input to the slot identification and enables the

SCANPSC110F for subsequent scan operations.

The Local Scan Port Network (LSPN) contains multiplexing

logic used to select different port configurations. The LSPN

control block contains the Local Scan Port Controllers

(LSPC) for each Local Scan Port (LSP1, LSP2, and LSP3).

This control block receives input from the SCANPSC110F

instruction register, mode register, and the TAP controller.

Each local port contains all four (4) boundary scan signals

needed to interface with the local TAPs.

SCANPSC110F BRIDGE STATE MACHINES

The SCANPSC110F is IEEE 1149.1-compatible, in that it

supports all required 1149.1 operations. In addition, it sup-

ports a higher level of protocol, (Level 1), that extends the

IEEE 1149.1 Std. to a multi-drop environment.

In multi-drop scan systems, a scan tester can select indi-

vidual SCANPSC110Fs for participation in upcoming scan

operations. SCANPSC110F “selection” is accomplished by

simultaneously scanning a device address out to multiple

SCANPSC110Fs. Through an on-chip address matching

process, only those SCANPSC110Fs whose statically-

assigned address matches the scanned-out address

become selected to receive further instructions from the

scan tester. SCANPSC110F selection is done using a

“Level-1” protocol, while follow-on instructions are sent to

selected SCANPSC110Fs by using a “Level-2” protocol.

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