Register Descriptions; Instruction Register (Instr); Table 14.2 Instruction Configuration - Hitachi H8S/2215 Series Hardware Manual

14.3

Register Descriptions

The boundary scan function has the following registers. These registers cannot be accessed by the
CPU.

• Instruction register (INSTR)

• IDCODE register (IDCODE)
• BYPASS register (BYPASS)
• Boundary scan register (BSCANR)
14.3.1 Instruction Register (INSTR)
INSTR is a 3-bit register. At initialization, this register is specified to IDCODE mode. When
TRST is pulled low, or when the TAP controller is in the Test-Logic-Reset state, INSTR is
initialized. INSTR can be written by the serial data input from the TDI. If more than three bits of
instruction is input from the TDI, INSTR stores the last three bits of serial data.
If a command reserved in INSTR is used, the correct operation cannot be guaranteed.
Bit Bit Name Initial Value R/W
2 TI2 1
1 TI1 0
0 TI0 1

Table 14.2 Instruction configuration

Bit 2 Bit1
TI2 TI1
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
Rev. 3.0, 10/02, page 420 of 686
Description
— Test Instruction Bits
Instruction configuration is shown in table 14.2.
—
—
Bit 0
TI0 Instruction
0 EXTEST
1 SAMPLE/PRELOAD
0 CLAMP
1 HIGHZ
0 Reserved
1 IDCODE (initial value)
0 Reserved
1 BYPASS