DSP56004ROM datasheet(23/82 Pages) FREESCALE

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Signal/Connection Descriptions

On-Chip Emulation (OnCETM) Port

MOTOROLA

DSP56004/D, Rev. 3

1-17

DSCK

OS1

Input

Output

Output,

Driven Low

Debug Serial Clock (DSCK)

—The DSCK/OS1 signal,

when an input, is the signal through which the serial clock

is supplied to the OnCE port. The serial clock provides

pulses required to shift data into and out of the OnCE port.

Data is clocked into the OnCE port on the falling edge and

is clocked out of the OnCE port on the rising edge.

Operating Status 1 (OS1)

—If the OS1 signal is an output

and used in conjunction with the OS0 signal, it provides

information about the DSP status when the DSP is not in the

Debug mode. The debug serial clock frequency must be no

greater than 1/8 of the processor clock frequency. The

signal is tri-stated when it is changing from input to output.

Note:

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

should be attached to the DSCK/OS1 pin. If the OnCE

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

DSO

Output

Driven High

Debug Serial Output (DSO)

—The DSO line provides the

data contained in one of the OnCE port controller registers

as specified by the last command received from the

command controller. The Most Significant Bit (MSB) of the

data word is always shifted out of the OnCE port first. Data

is clocked out of the OnCE port on the rising edge of DSCK.

The DSO line also provides acknowledge pulses to the

external command controller. When the DSP enters the

Debug mode, the DSO line will be pulsed low to indicate

that the OnCE port is waiting for commands. After

receiving a read command, the DSO line will be pulsed low

to indicate that the requested data is available and the

OnCE port is ready to receive clock pulses in order to

deliver the data. After receiving a write command, the DSO

line will be pulsed low to indicate that the OnCE port is

ready to receive the data to be written; after the data is

written, another acknowledge pulse will be provided.

Note:

During hardware reset and when idle, the DSO line is

held high.

Table 1-12

On-Chip Emulation Port Signals (Continued)

Signal

Name

Signal

Type

State during

Reset

Signal Description

Freescale Semiconductor, Inc.

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DSP56004ROM Datasheet(PDF) 23 Page - Freescale Semiconductor, Inc

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