PD46184184B Datasheet, PDF (30/39 Pages) Renesas Technology Corp – 18M-BIT DDR II SRAM 4-WORD BURST OPERATION

μPD46185084B, μPD46185094B, μPD46185184B, μPD46185364B
JTAG Instructions
Instructions
Description
EXTEST
The EXTEST instruction allows circuitry external to the component package to be tested.
Boundary-scan register cells at output pins are used to apply test vectors, while those at
input pins capture test results. Typically, the first test vector to be applied using the
EXTEST instruction will be shifted into the boundary scan register using the PRELOAD
instruction. Thus, during the update-IR state of EXTEST, the output drive is turned on and
the PRELOAD data is driven onto the output pins.
IDCODE
BYPASS
The IDCODE instruction causes the ID ROM to be loaded into the ID register when the
controller is in capture-DR mode and places the ID register between the TDI and TDO pins
in shift-DR mode. The IDCODE instruction is the default instruction loaded in at power up
and any time the controller is placed in the test-logic-reset state.
When the BYPASS instruction is loaded in the instruction register, the bypass register is
placed between TDI and TDO. This occurs when the TAP controller is moved to the shift-
DR state. This allows the board level scan path to be shortened to facilitate testing of other
devices in the scan path.
SAMPLE / PRELOAD SAMPLE / PRELOAD is a Standard 1149.1 mandatory public instruction. When the
SAMPLE / PRELOAD instruction is loaded in the instruction register, moving the TAP
controller into the capture-DR state loads the data in the RAMs input and Q pins into the
boundary scan register. Because the RAM clock(s) are independent from the TAP clock
(TCK) it is possible for the TAP to attempt to capture the I/O ring contents while the input
buffers are in transition (i.e., in a metastable state). Although allowing the TAP to sample
metastable input will not harm the device, repeatable results cannot be expected. RAM
input signals must be stabilized for long enough to meet the TAPs input data capture setup
plus hold time (tCS plus tCH). The RAMs clock inputs need not be paused for any other
TAP operation except capturing the I/O ring contents into the boundary scan register.
Moving the controller to shift-DR state then places the boundary scan register between the
TDI and TDO pins.
SAMPLE-Z
If the SAMPLE-Z instruction is loaded in the instruction register, all RAM Q pins are forced
to an inactive drive state (high impedance) and the boundary register is connected between
TDI and TDO when the TAP controller is moved to the shift-DR state.
JTAG Instruction Coding
IR2
IR1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
IR0
Instruction
0
EXTEST
1
IDCODE
0
SAMPLE-Z
1
RESERVED
0
SAMPLE / PRELOAD
1
RESERVED
0
RESERVED
1
BYPASS
Notes 1. TRISTATE all Q pins and CAPTURE the pad values into a SERIAL SCAN LATCH.
2. Do not use this instruction code because the vendor uses it to evaluate this product.
Note
1
2
2
2
R10DS0113EJ0200 Rev.2.00
Nov 09, 2012
Page 30 of 38