5.10.2
Instruction Register and Supported Instructions
The instruction register is a 4-bit register that enacts the boundary scan instructions. After the state
machine resets, the default instruction is IDCODE. The decode logic in the TAP controller selects
the appropriate data register and configures the boundary scan cells for the current instruction.
Table 38
shows the supported boundary-scan instructions.
Table 38. Instruction Register Description
Instruction
BYPASS
EXTEST
SAMPLE
IDCODE
HIGHZ
CLAMP
Datasheet
Document Number: 278757
Revision Number: 009
Revision Date: 27-Oct-2005
®
Intel
IXF1104 4-Port Gigabit Ethernet Media Access Controller
Code
Description
1111
1-bit Bypass
0000
External Test
0001
Sample Boundary
0110
ID Code Inspection
0101
Float Boundary
0111
Clamp Boundary
Data Register
Bypass
Boundary Scan
Boundary Scan
ID
Bypass
Bypass
124