ATF1508AS datasheet(13/22 Pages) ATMEL

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ATF1508AS/Z

JTAG-BST Overview

The JTAG boundary-scan testing is controlled by the Test

Access Port (TAP) controller in the ATF1508AS. The

boundary-scan technique involves the inclusion of a shift-

to each component so that signals at component bound-

aries can be controlled and observed using scan testing

principles. Each input pin and I/O pin has its own boundary

scan cell (BSC) in order to support boundary scan testing.

The ATF1508AS does not currently include a Test Reset

(TRST) input pin because the TAP controller is automati-

cally reset at power up. The six JTAG BST modes sup-

ported include: SAMPLE/PRELOAD, EXTEST, BYPASS,

IDCODE. BST on the ATF1508AS is implemented using

the Boundary Scan Definition Language (BSDL) described

in the JTAG specification (IEEE Standard 1149.1). Any

third party tool that supports the BSDL format can be used

to perform BST on the ATF1508AS.

The ATF1508AS also has the option of using four JTAG-

standard I/O pins for in-system programming (ISP). The

ATF1508AS is programmable through the four JTAG pins

using programming compatible with the IEEE JTAG Stan-

dard 1149.1. Programming is performed by using 5V TTL-

level programming signals from the JTAG ISP interface.

The JTAG feature is a programmable option. If JTAG (BST

or ISP) is not needed, then the four JTAG control pins are

available as I/O pins.

JTAG Boundary Scan Cell (BSC)

Testing

The ATF1508AS contains up to 96 I/O pins and 4 input

pins, depending on the device type and package type

selected. Each input pin and I/O pin has its own boundary

scan cell (BSC) in order to support boundary scan testing

as described in detail by IEEE Standard 1149.1. Typical

BSC consists of three capture registers or scan registers

and up to two update registers. There are two types of

BSCs, one for input or I/O pin, and one for the macrocells.

The BSCs in the device are chained together through the

capture registers. Input to the capture register chain is fed

in from the TDI pin while the output is directed to the TDO

pin. Capture registers are used to capture active device

data signals, to shift data in and out of the device and to

load data into the update registers. Control signals are gen-

erated internally by the JTAG TAP controller. The BSC

configuration for the input and I/O pins and macrocells are

shown below.

BSC Configuration Pins and

Macrocells (except JTAG TAP Pins)

Note:

The ATF1508AS has pull-up option on TMS and TDI

pins. This feature is selected as a design option.

ATF1508AS 数据表(PDF) 13 Page - ATMEL Corporation

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