Datasheet
3−11
3.15 JTAG Support
The PCI2050B bridge implements a JTAG test port based on IEEE Standard 1149.1, IEEE Standard Test Access Port
and Boundary-Scan Architecture. The JTAG test port consists of the following:
• A 5-wire test access port
• A test access port controller
• An instruction register
• A bypass register
• A boundary-scan register
3.15.1 Test Port Instructions
The PCI2050B bridge supports the following JTAG instructions:
• EXTEST, BYPASS, and SAMPLE
• HIGHZ and CLAMP
• Private (various private instructions used by TI for test purposes)
Table 3−4 lists and describes the different test port instructions, and gives the op code of each one. The information
in Table 3−5 is for implementation of boundary scan interface signals to permit in-circuit testing.
Table 3−4. JTAG Instructions and Op Codes
INSTRUCTION OP CODE DESCRIPTION
EXTEST 00000 External test: drives terminals from the boundary scan register
SAMPLE 00001 Sample I/O terminals
CLAMP 00100 Drives terminals from the boundary scan register and selects the bypass register for shifts
HIGHZ 00101 Puts all outputs and I/O terminals except for the TDO terminal in a high-impedance state
BYPASS 11111 Selects the bypass register for shifts
Table 3−5. Boundary Scan Terminal Order
BOUNDARY SCAN
REGISTER NUMBER
PDV/PPM TERMINAL
NUMBER
GHK/ZHK
TERMINAL NUMBER
TERMINAL
NAME
GROUP DISABLE
REGISTER
BOUNDARY-SCAN
CELL TYPE
0 137 J15 S_AD0 19 Bidirectional
1 138 H19 S_AD1 19 Bidirectional
2 140 H17 S_AD2 19 Bidirectional
3 141 H14 S_AD3 19 Bidirectional
4 143 G19 S_AD4 19 Bidirectional
5 144 G18 S_AD5 19 Bidirectional
6 146 G14 S_AD6 19 Bidirectional
7 147 F19 S_AD7 19 Bidirectional
8 149 G15 S_C/BE0 19 Bidirectional
9 150 F17 S_AD8 19 Bidirectional
10 152 F14 S_AD9 19 Bidirectional
11 153 E18 S_M66ENA 19 Bidirectional
12 154 F15 S_AD10 19 Bidirectional
13 155 E17 MS0 − Input
14 158 E14 S_AD11 19 Bidirectional
15 161 B15 S_AD12 19 Bidirectional
16 162 A15 S_AD13 19 Bidirectional
17 164 B14 S_AD14 19 Bidirectional
18 165 E13 S_AD15 19 Bidirectional
19 − − − − Control