32186 datasheet(898/1032 Pages) RENESAS

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JTAG

21-4

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

21.3 JTAG Registers

21.3.1 Instruction Register (JTAGIR)

The Instruction Register is a 6-bit register to hold instruction code. This register is set in the IR path sequence. The

instructions set in this register determine the data register to be selected in the subsequent DR path sequence.

The initial value of this register after test is reset (to initialize the test circuit) is b’000010 (IDCODE instruc-

tion). After a test reset, the ID Code Register is selected as the data register until instruction code is set by

an external device. In the Capture-IR state, this register always has b’110001 (fixed value) loaded into it.

Therefore, when in the Shift-IR state, no matter what value was set in this register, the value b’110001 is

always output from the JTDO pin (sequentially beginning with the LSB). However, this value normally is not

handled as instruction code.

Shown below is outside the scope of guaranteed operations. If this operation is attempted, the microcom-

puter may handle b’110001 as instruction code, which makes the microcomputer unable to operate normally.

Capture-IR

→ Exit1-IR → Update-IR

Following instructions are supported for the JTAG interface of the M32R/ECU:

• Three instructions specified as essential in IEEE 1149.1 (EXTEST, SAMPLE/PRELOAD, BYPASS)

• Device identification register access instruction (IDCODE)

Table 21.3.1 JTAG Instruction List

Instruction Code

Abbreviation

Operation

b'000000

EXTEST

Test the circuit/board-level connections external to the chip.

b'000001

SAMPLE/PRELOAD Sample the operating status of the circuit and output the sampled status from the

JTDO pin, while at the same time supplying the data used for boundary-scan test

from the JTDI pin and preset it in the Boundary Scan Register.

b'000010

IDCODE

Select the ID Code Register to output the device and manufacturer

identification data from the JTDO pin.

b'111111

BYPASS

Select the Bypass Register to inspect or set data.

Notes: • Do not set any other instruction code.

• For details about the IR path sequence, DR path sequence, test reset, Capture-IR state, Shift-IR state, Exit1-IR state

and Update-IR state, see Section 21.4, “Basic Operation of JTAG.”

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