TMS320VC5409_16 Datasheet, PDF (20/93 Pages) Texas Instruments – Digital Signal Processor

Introduction
Table 2−2. Terminal Functions (Continued)
TERMINAL
NAME
INTERNAL
PIN STATE
I/O†
DESCRIPTION
TEST PINS
TCK
Schmitt
trigger/pullup
resistor
IEEE standard 1149.1 test clock. TCK is normally a free-running clock signal with a 50% duty cycle.
I
The changes on the test access port (TAP) of input signals TMS and TDI are clocked into the TAP
controller, instruction register, or selected test data register on the rising edge of TCK. Changes at
the TAP output signal (TDO) occur on the falling edge of TCK.
TDI
Pullup
resistor
I
IEEE standard 1149.1 test data input pin with internal pullup device. TDI is clocked into the selected
register (instruction or data) on a rising edge of TCK.
TDO
IEEE standard 1149.1 test data output. The contents of the selected register (instruction or data)
O/Z are shifted out of TDO on the falling edge of TCK. TDO is in the high-impedance state except when
the scanning of data is in progress. TDO also goes into the high-impedance state when OFF is low.
TMS
Pullup
resistor
IEEE standard 1149.1 test mode select. Pin with internal pullup device. This serial control input is
I
clocked into the TAP controller on the rising edge of TCK.
TRST‡
Pulldown
resistor
IEEE standard 1149.1 test reset. TRST, when high, gives the IEEE standard 1149.1 scan system
I
control of the operations of the device. If TRST is driven low, the device operates in its functional
mode, and the IEEE standard 1149.1 signals are ignored. Pin with internal pulldown device.
EMU0
I/O/Z
Emulator 0 pin. When TRST is driven low, EMU0 must be high for activation of the OFF condition.
When TRST is driven high, EMU0 is used as an interrupt to or from the emulator system and is
defined as input/output by way of the IEEE standard 1149.1 scan system.
EMU1/OFF
I/O/Z
Emulator 1 pin/disable all outputs. When TRST is driven high, EMU1/OFF is used as an interrupt
to or from the emulator system and is defined as input/output by way of the IEEE standard 1149.1
scan system. When TRST is driven low, EMU1/OFF is configured as OFF. The EMU1/OFF signal,
when active low, puts all output drivers into the high-impedance state. Note that OFF is used
exclusively for testing and emulation purposes (not for multiprocessing applications). Therefore, for
the OFF feature, the following apply:
TRST = low
EMU0 = high
EMU1/OFF = low
† _{I = Input, O = Output, Z = High-impedance, S = Supply}
‡ _{Although this pin includes an internal pulldown resistor, a 470-Ω external pulldown is required. If the TRST pin is connected to multiple DSPs,}
a buffer is recommended to ensure the VIL and VIH specifications are met.
20 _SPRS082F
April 1999 − Revised October 2008