D-35
SYSTEM REGISTER QUICK REFERENCE
D.32 IR
Instruction Register
IR Reset State
(Using TRST#): 02H
30
INST3 INST2 INST1 INST0
Bit
Number Bit
Mnemonic Function
3–0 INST3:0 Instruction opcode. At reset (using TRST# , or after 5 TCK cycles with
TMS held low), this field is loaded with 00 10, the opcode for th e IDCODE
instruction. Instructions are shifted into this field serially through the TDI
pin. (Table 18-4 lists the valid instruction opcodes.)