RX610 Group
28. Boundary Scan
R01UH0032EJ0120 Rev.1.20
Page 950 of 1006
Feb 20, 2013
28.3.2
List of Commands
(1) BYPASS [Instruction Code: 1111b]
The BYPASS instruction is an instruction that drives the bypass register (JTBPR). This instruction shortens the shift
path, facilitating the transfer of serial data to other LSIs on a printed-circuit board at higher speeds. While this instruction
is being executed, the test circuit has no effect on the system circuits.
The bypass register (JTBPR) is connected between the TDI and TDO pins. Bypass operation is initiated from shift-DR
operation. The TDO is low in the first clock cycle in the shift-DR state; in the subsequent clock cycles, the TDI signal is
output on the TDO pin.
(2) EXTEST [Instruction Code: 0000b]
The EXTEST instruction is used to test external circuits when this LSI is installed on the printed circuit board. If this
instruction is executed, output pins are used to output test data (specified by the SAMPLE/PRELOAD instruction) from
the boundary scan register to the print circuit board, and input pins are used to input test result.
(3) SAMPLE/PRELOAD [Instruction Code: 0001b]
The SAMPLE/PRELOAD instruction is used to input data from the LSI internal circuits to the boundary scan register,
output data from scan path, and reload the data to the scan path. While this instruction is executed, input signals are
directly input to the LSI and output signals are also directly output to the external circuits. The LSI system circuit is not
affected by this instruction.
In SAMPLE operation, the boundary scan register latches the snap shot of data transferred from input pins to internal
circuit or data transferred from internal circuit to output pins. The latched data is read from the scan path. The scan
register latches the snap data at the rising edge of the TCK in Capture-DR state. The scan register latches snap shot
without affecting the LSI normal operation.
In PRELOAD operation, initial value is written from the scan path to the parallel output latch of the boundary scan
register prior to the EXTEST instruction execution. If the EXTEST is executed without executing this PRELOAD
operation, undefined values are output from the beginning to the end (transfer to the output latch) of the EXTEST
sequence. (In EXTEST instruction, output parallel latches are always output to the output pins.)
(4) IDCODE [Instruction Code: 0100b]
When the IDCODE instruction is selected, IDCODE register value is output to the TDO in Shift-DR state of the TAP
controller. In this case, IDCODE register value is output from the LSB. During this instruction execution, test circuit
does not affect the system circuit. INSTR is initialized by the IDCODE instruction in Test-Logic-Reset state of the TAP
controller.
