Renesas H8S Series Hardware Manual page 893

(3) EXTEST
Instruction code: B'0000
The EXTEST instruction is provided to test external circuitry when this LSI is mounted on a
printed circuit board. When this instruction is executed, output pins are used to output test data
(previously set by the SAMPLE/PRELOAD instruction) from the boundary scan register to the
printed circuit board, and input pins are used to latch test results into the boundary scan register
from the printed circuit board. If testing is carried out by using the EXTEST instruction N times,
the Nth test data is scanned in when test data (N-1) is scanned out.
Data loaded into the output pin boundary scan register in the Capture-DR state is not used for
external circuit testing (it is replaced by a shift operation).
(4) CLAMP
Instruction code: B'0010
When the CLAMP instruction is enabled, the output pin outputs the value of the boundary scan
register that has been previously set by the SAMPLE/PRELOAD instruction. While the CLAMP
instruction is enabled, the state of the boundary scan register maintains the previous state
regardless of the state of the TAP controller.
A bypass register is connected between the ETDI and ETDO pins. The related circuit operates in
the same way when the BYPASS instruction is enabled.
(5) HIGHZ
Instruction code: B'0011
When the HIGHZ instruction is enabled, all output pins enter a high-impedance state. While the
HIGHZ instruction is enabled, the state of the boundary scan register maintains the previous state
regardless of the state of the TAP controller.
A bypass register is connected between the ETDI and ETDO pins. The related circuit operates in
the same way when the BYPASS instruction is enabled.
Section 22 Boundary Scan (JTAG)
Rev. 3.00 Jul. 14, 2005 Page 845 of 986
REJ09B0098-0300