19
19-4
JTAG
32180 Group User's Manual (Rev.1.0)
19.3 JTAG Registers
19.3 JTAG Registers
19.3.1 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 instruction).
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 microcomputer
may inadvertently 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 stipulated as essential in IEEE 1149.1 (EXTEST, SAMPLE/PRELOAD, BYPASS)
• Device identification register access instruction (IDCODE)
Table 19.3.1 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 and output the device and manufacturer
identification data from the JTDO pin.
b'111111 BYPASS Select the Bypass Register and 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 19.4, “Basic Operation of JTAG.”
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