Datasheet

DS26504 T1/E1/J1/64KCC BITS Element
103 of 129
17. JTAG BOUNDARY SCAN ARCHITECTURE AND TEST ACCESS PORT
The DS26504 supports the standard IEEE 1149.1 instruction codes SAMPLE/PRELOAD, BYPASS, and
EXTEST. Optional public instructions included are HIGHZ, CLAMP, and IDCODE. The DS26504
contains the following as required by IEEE 1149.1 Standard Test Access Port and Boundary Scan
Architecture:
 Test Access Port (TAP)
 TAP Controller
 Instruction Register
 Bypass Register
 Boundary Scan Register
 Device Identification Register
Details on Boundary Scan Architecture and the Test Access Port can be found in IEEE 1149.1-1990,
IEEE 1149.1a-1993, and IEEE 1149.1b-1994.
The Test Access Port has the necessary interface pins: JTRST, JTCLK, JTMS, JTDI, and JTDO. See the
pin descriptions for details.
Figure 17-1. JTAG Functional Block Diagram
JTDI JTMS JTCLK
J
TRST
JTDO
TEST ACCESS PORT
CONTROLLER
V
DD
V
DD
V
DD
BOUNDRY SCAN
REGISTER
BYPASS
REGISTER
INSTRUCTION
REGISTER
IDENTIFICATION
REGISTER
MUX
SELECT
OUTPUT ENABLE
10kΩ 10kΩ 10k
Ω