DSP56004ROM datasheet(22/82 Pages) FREESCALE

22 / 82 page

1-16

DSP56004/D, Rev. 3

MOTOROLA

Signal/Connection Descriptions

General Purpose I/O

GENERAL PURPOSE I/O

ON-CHIP EMULATION (OnCETM) PORT

There are four signals associated with the OnCE port controller and its serial

interface.

Table 1-11

General Purpose I/O (GPIO) Signals

Signal

Name

Signal

Type

State during

Reset

Signal Description

GPIO0–

GPIO3

Standard

Output,

Open-drain

Output, or

Input

Disconnected

GPIO lines can be used for control and handshake

functions between the DSP and external circuitry.

Each GPIO line can be configured individually as

disconnected, open-drain output, standard output,

or an input.

Note:

Hardware reset or software reset configures all

the GPIO lines as disconnected (external

circuitry connected to these pins may need pull-

ups until the pins are configured for operation).

Table 1-12

On-Chip Emulation Port Signals

Signal

Name

Signal

Type

State during

Reset

Signal Description

DSI

OS0

Input

Output

Output,

Driven Low

Debug Serial Input (DSI)

—The DSI signal is the signal

through which serial data or commands are provided to the

OnCE port controller. The data received on the DSI signal

will be recognized only when the DSP has entered the

Debug mode of operation. Data must have valid TTL logic

levels before the serial clock falling edge. Data is always

shifted into the OnCE port Most Significant Bit (MSB) first.

Operating Status 0 (OS0)—

When the DSP is not in the Debug

mode, the OS0 signal provides information about the DSP

status if it is an output and used in conjunction with the OS1

signal. When switching from output to input, the signal is

tri-stated.

Note:

If the OnCE port is in use, an external pull-down resistor

should be attached to the DSI/OS0 signal. If the OnCE

port is not in use, the resistor is not required.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

DSP56004ROM Datasheet(PDF) 22 Page - Freescale Semiconductor, Inc

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