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IDT EJTAG System
EJTAG Test Access Port
79RC32438 User Reference Manual
20 - 61
November 4, 2002
Notes
to the register when a processor reset is applied. If a power-up state is specified, then the indicated value is
applied at power-up reset. JTAG_TCK does not have to be running in order for a processor reset to reset
the registers.
Device Identification (ID) Register (TAP Instruction IDCODE)
Compliance Level
: Required with EJTAG TAP feature.
The Device ID register is a 32-bit read-only register that identifies the specific device implementing
EJTAG. This register is also defined in IEEE 1149.1. The Device ID register holds a unique number among
different devices with EJTAG compliant processors implemented. It is recommended that the register is
also unique amongst different EJTAG compliant processors in the same device. Figure 20.28 shows the
format of the Device ID register and Table 20.43 describes the Device ID register fields
31
28 27
12 11
1
0
1
Version
0000
PartNumber
0022
ManufID
033
Figure 20.28 Device ID Register Format
Fields
Description
Read/
Write
Power-up
State
Compli-
ance
Name
Bits
Version
31_28
Identifies the version of a specific device.
The value in this field must be unique for
particular values of Manufacturer ID and
Part Number values. The value identifies a
specific revision of the design (such as a
sequence of bug fixes within the same
major design). The value is assigned by
the design house.
R
Preset
Required
Part
Number
27:12
Identifies the part number of a specific
device.
The value in this field must be unique for a
particular Manufacturer ID value.
Design houses which wish to use the MIPS
Technologies, Inc. Manufacturer ID may
request assignment of a group of Part
Numbers which are then managed by that
design house. Assignment of Part Num-
bers within another Manufacturer ID value
is done by the owner of that Manufacturer
ID.
R
Preset
Required
Table 20.43 Device ID Register Field Description (Part 1 of 2)