GS816272C
Register, under the control of the TAP Controller, is loaded with the contents of the RAMs I/O ring when the controller is in
Capture-DR state and then is placed between the TDI and TDO pins when the controller is moved to Shift-DR state. SAMPLE-Z,
SAMPLE/PRELOAD and EXTEST instructions can be used to activate the Boundary Scan Register.
JTAG TAP Block Diagram
····· ···
Boundary Scan Register
·
·
·
0
Bypass Register
210
Instruction Register
TDI
TDO
ID Code Register
· 31 30 29 · · · 2 1 0
Control Signals
TMS
TCK
Test Access Port (TAP) Controller
Identification (ID) Register
The ID Register is a 32-bit register that is loaded with a device and vendor specific 32-bit code when the controller is put in
Capture-DR state with the IDCODE command loaded in the Instruction Register. The code is loaded from a 32-bit on-chip ROM.
It describes various attributes of the RAM as indicated below. The register is then placed between the TDI and TDO pins when the
controller is moved into Shift-DR state. Bit 0 in the register is the LSB and the first to reach TDO when shifting begins.
Rev: 2.18 11/2005
21/31
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
© 1999, GSI Technology