13. JTAG > TAP Controller Initialization
110
PEB383 User Manual
July 25, 2011
Integrated Device Technology, Inc.
Confidential - NDA Required
— Bypass
— IDCODE
— Clamp
— User data select
13.2
TAP Controller Initialization
After power-up of the PEB383, the TAP controller must be put into its test-logic-reset state to disable
the JTAG logic and allow the bridge to function normally. This can be completed by driving the
JTAG_TMS signal high and pulsing the JTAG_TCK signal five or more times, or by asserting the
JTAG_TRSTn signal.
13.3
Instruction Register
The PEB383 uses an Instruction register to control the operation of the JTAG logic. Bit combinations
that are not equivalent to any instruction are equivalent to the BYPASS instruction.
13.4
Bypass Register
This register is a 1-bit shift register that provides a single bit scan path between the JTAG_TDI input
and the JTAG_TDO output. This abbreviated scan path is selected by the BYPASS instruction code,
and is used to shorten the overall scan ring length during board-level testing when the PEB383 is not
involved.
13.5
JTAG Device ID Register
The JTAG device identification number for the PEB383 is as follows:
•
Version [31:28] – 0000
•
Part number [27:12] – 0000_0011_1000_0011
•
Manufacturer identity [11:1] – 000_1011_0011
•
Mandatary LSB [0] – 1