Clamp (B[3:0] = 0011); Figure 11-4 Jtag Id Register - Motorola DSP56305 User Manual

JTAG Port
TAP Controller
31 28 27
Version
Information
0 0 0 0 0 0 0 1 1 0
One application of the ID register is to distinguish the manufacturer(s) of components on
a board when multiple sourcing is used. As more components emerge which conform to
the IEEE 1149.1 standard, it is desirable to allow for a system diagnostic controller unit to
blindly interrogate a board design in order to determine the type of each component in
each location. This information is also available for factory process monitoring and for
failure mode analysis of assembled boards.
Motorola's Manufacturer Identity is 00000001110. The Customer Part Number consists
of two parts: Motorola Design Center Number (bits 27:22) and a sequence number (bits
21:12). The sequence number is divided into two parts: Core Number (bits 21:17) and
Chip Derivative Number (bits 16:12). Motorola Semiconductor IsraeL (MSIL) Design
Center Number is 000110 and DSP56300 core number is 00001. For the DSP56305, the
chip derivative number is 00011.
Once the IDCODE instruction is decoded, it selects the ID register, which is a 32-bit data
register. The Bypass register loads a logic 0 at the start of a scan cycle, whereas the ID
register loads a logic 1 into its Least Significant Bit; thus, examination of the first bit of
data shifted out of a component during a test data scan sequence immediately following
exit from Test-Logic-Reset controller state shows whether such a register is included in
the design. When the IDCODE instruction is selected, the operation of the test logic has
no effect on the operation of the on-chip system logic as required by the IEEE 1149.1
standard.
11.3.2.4

CLAMP (B[3:0] = 0011)

The CLAMP instruction is not included in the IEEE 1149.1 standard. It is provided as a
public instruction that selects the 1-bit Bypass register as the serial path between TDI
and TDO while allowing signals driven from the component signals to be determined
from the BSR. During testing of ICs on PCB, it may be necessary to place static guarding
values on signals that control operation of logic not involved in the test. The EXTEST
instruction could be used for this purpose, but since it selects the Boundary Scan
11-10
22 21 17
Customer Part Number
Design
Core
Center
Number
Number
0 0 0 0 0

Figure 11-4 JTAG ID Register

DSP56305 User's Manual
16 12 11
Manufacturer
Chip
Derivative
Number
0 0 0 1 1 0 0 0 0 0 0 0 1 1 1 0
1 0
1
Identity
1
AA0718
MOTOROLA