GS8162Z18(B/D)/GS8162Z36(B/D)/GS8162Z72(C)
Typically, the Boundary Scan Register is loaded with the desired pattern of data with the SAMPLE/PRELOAD command.
Then the EXTEST command is used to output the Boundary Scan Register’s contents, in parallel, on the RAM’s data output
drivers on the falling edge of TCK when the controller is in the Update-IR state.
Alternately, the Boundary Scan Register may be loaded in parallel using the EXTEST command. When the EXTEST instruc-
tion is selected, the sate of all the RAM’s input and I/O pins, as well as the default values at Scan Register locations not asso-
ciated with a pin, are transferred in parallel into the Boundary Scan Register on the rising edge of TCK in the Capture-DR
state, the RAM’s output pins drive out the value of the Boundary Scan Register location with which each output pin is associ-
ated.
IDCODE
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.
SAMPLE-Z
If the SAMPLE-Z instruction is loaded in the instruction register, all RAM outputs are forced to an inactive drive state (high-
Z) and the Boundary Scan Register is connected between TDI and TDO when the TAP controller is moved to the Shift-DR
state.
RFU
These instructions are Reserved for Future Use. In this device they replicate the BYPASS instruction.
JTAG TAP Instruction Set Summary
Instruction
EXTEST
IDCODE
Code
000
001
Description
Notes
1
1, 2
Places the Boundary Scan Register between TDI and TDO.
Preloads ID Register and places it between TDI and TDO.
Captures I/O ring contents. Places the Boundary Scan Register between TDI and
SAMPLE-Z
010
011
TDO.
1
1
Forces all RAM output drivers to High-Z.
Do not use this instruction; Reserved for Future Use.
Replicates BYPASS instruction. Places Bypass Register between TDI and TDO.
RFU
SAMPLE/
PRELOAD
Captures I/O ring contents. Places the Boundary Scan Register between TDI and
TDO.
GSI private instruction.
Do not use this instruction; Reserved for Future Use.
Replicates BYPASS instruction. Places Bypass Register between TDI and TDO.
100
101
110
111
1
1
1
1
GSI
RFU
BYPASS
Places Bypass Register between TDI and TDO.
Notes:
1. Instruction codes expressed in binary, MSB on left, LSB on right.
2. Default instruction automatically loaded at power-up and in test-logic-reset state.
Rev: 2.21 11/2004
28/38
© 1999, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GSI [ GSI TECHNOLOGY ]
