TMS320VC33

DIGITAL SIGNAL PROCESSOR

SPRS087E − FEBRUARY 1999 − REVISED JANUARY 2004

20

POST OFFICE BOX 1443

JTAG emulation

Though the TMS320VC33 contains a JTAG debug port which allows multiple JTAG enabled chips to be

daisy-chained, boundary scan of the pins is not supported. If the pin scan path is selected, it will be routed

through a null register with a length of one. For additional information concerning the emulation interface, see

JTAG/MPSD Emulation Technical Reference (literature number SPDU079).

designing your target system’s emulator connector (14-pin header)

JTAG target devices support emulation through a dedicated emulation port. This port is a superset of the

IEEE 1149.1 standard and is accessed by the emulator. To communicate with the emulator, your target system

must have a 14-pin header (two rows of seven pins) with the connections that are shown in Figure 11. Table 6

describes the emulation signals.

TDO

7

8

GND

TMS

1

2

TRST

TDI

3

4

GND

TCK_RET

9

10

GND

TCK

11

12

GND

Header Dimensions:

Pin-to-pin spacing, 0.100 in. (X,Y)

Pin width, 0.025-in. square post

Pin length, 0.235-in. nominal

6

EMU0

13

14

EMU1

† While the corresponding female position on the cable connector is plugged to prevent improper

connection, the cable lead for pin 6 is present in the cable and is grounded, as shown in the

schematics and wiring diagrams in this document.

Figure 11. 14-Pin Header Signals and Header Dimensions

Table 6. 14-Pin Header Signal Descriptions

SIGNAL

DESCRIPTION

EMULATOR†

STATE

TARGET†

STATE

TMS‡

Test mode select

O

I

TDI

Test data input

O

I

TDO

Test data output

I

O

TCK

Test clock. TCK is a 10.368-MHz clock source from the emulation cable pod.

This signal can be used to drive the system test clock

O

I

TRST‡

Test reset

O

I

EMU0§¶

Emulation pin 0

I

I/O

EMU1§¶

Emulation pin 1

I

I/O

PD(VCC)

Presence detect. Indicates that the emulation cable is connected and that the

target is powered up. PD should be tied to VCC in the target system.

I

O

TCK_RET

Test clock return. Test clock input to the emulator. May be a buffered or unbuf-

fered version of TCK.

I

O

GND

Ground

† I = input; O = output

‡ Use 1−50K pulldown for TRST. Do not use pullup resistors on TRST: it has an internal pulldown device. In a low-noise environment, TRST can

be left floating. In a high-noise environment, an additional pulldown resistor may be needed. (The size of this resistor should be based on electrical

current considerations.)

§ Use 1−50K pullups for TMS, EMU0 and EMU1.

¶ EMU0 and EMU1 are I/O drivers configured as open-drain (open-collector) drivers. They are used as bidirectional signals for emulation global

start and stop.