OTB25LPLL datasheet(15/174 Pages) ACTEL

15 / 174 page

ProASICPLUS Flash Family FPGAs

v5.2

1-11

Boundary Scan (JTAG)

ProASICPLUS devices are compatible with IEEE Standard

1149.1, which defines a set of hardware architecture and

mechanisms for cost-effective, board-level testing. The

basic ProASICPLUS boundary-scan logic circuit is composed

of the TAP (test access port), TAP controller, test data

registers, and instruction register (Figure 1-12). This

circuit supports all mandatory IEEE 1149.1 instructions

(EXTEST,

SAMPLE/PRELOAD

and

BYPASS)

and

the

optional IDCODE instruction (Table 1-6).

Each test section is accessed through the TAP, which has

five associated pins: TCK (test clock input), TDI and TDO

(test data input and output), TMS (test mode selector)

and TRST (test reset input). TMS, TDI and TRST are

equipped with pull-up resistors to ensure proper

operation when no input data is supplied to them. These

pins are dedicated for boundary-scan test usage. Actel

recommends that a nominal 20 k

Ω pull-up resistor is

added to TDO and TCK pins.

The TAP controller is a four-bit state machine (16 states)

that operates as shown in Figure 1-13 on page 1-12. The

’1’s and ‘0’s represent the values that must be present at

TMS at a rising edge of TCK for the given state transition

to occur. IR and DR indicate that the instruction register

or the data register is operating in that state.

ProASICPLUS devices have to be programmed at least

once for complete boundary-scan functionality to be

available. If boundary-scan functionality is required prior

to programming, refer to online technical support on the

Actel website and search for ProASICPLUS BSDL.

Figure 1-12 • ProASICPLUS JTAG Boundary Scan Test Logic Circuit

Device

Logic

I/O

Bypass Register

Instruction

TAP

Controller

Test Data

Registers

Table 1-6 •

Boundary-Scan Opcodes

Hex Opcode

EXTEST

SAMPLE/PRELOAD

IDCODE

CLAMP

BYPASS

OTB25LPLL 数据表(PDF) 15 Page - Actel Corporation

OTB25LPLL 数据表(HTML) 15 Page - Actel Corporation

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