DS31256 datasheet(163/183 Pages) MAXIM

No de pièce	DS31256

Description	256-Channel, High-Throughput HDLC Controller

PDF	183 Pages

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Fabricant	MAXIM [Maxim Integrated Products]

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DS31256 256-Channel, High-Throughput HDLC Controller

163 of 183

12.

JTAG

12.1JTAG Description

The DS31256 supports the standard instruction codes SAMPLE/PRELOAD, BYPASS, and EXTEST.

Optional public instructions included are HIGHZ, CLAMP, and IDCODE. Figure 12-1 is a block

diagram. The DS31256 contains the following items, which meet the requirements set by the IEEE

1149.1 Standard Test Access Port and Boundary Scan Architecture:

Test Access Port (TAP)

TAP Controller

Instruction Register

Bypass Register

Boundary Scan Register

Device Identification Register

The TAP has the necessary interface pins JTCLK,

JTRST, JTDI, JTDO, and JTMS. Details about these

pins can be found in Section 3.4. Refer to IEEE 1149.1-1990, IEEE 1149.1a-1993, and IEEE 1149.1b-

1994 for details about the Boundary Scan Architecture and the TAP.

Figure 12-1. Block Diagram

BOUNDARY

SCAN REGISTER

IDENTIFICATION

BYPASS

INSTRUCTION

TEST ACCESS PORT

CONTROLLER

SELECT

TRI-STATE

JTDI

10k

JTMS

10k

JTCLK

JTRST

10k

JTDO

DS31256 Fiches technique(PDF) 163 Page - Maxim Integrated Products