DSP56004ROM datasheet(24/82 Pages) FREESCALE

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1-18

DSP56004/D, Rev. 3

MOTOROLA

Signal/Connection Descriptions

On-Chip Emulation (OnCETM) Port

Input

Debug Request (DR)

—The debug request input provides a

means of entering the Debug mode of operation. This signal,

when asserted (pulled low), will cause the DSP to finish the

current instruction being executed, to save the instruction

pipeline information, to enter the Debug mode, and to wait

for commands to be entered from the debug serial input line.

While the DSP is in the Debug mode, the user can reset the

OnCE port controller by asserting DR, waiting for an

acknowledge pulse on DSO, and then deasserting DR. It

may be necessary to reset the OnCE port controller in cases

where synchronization between the OnCE port controller

and external circuitry is lost. Asserting DR when the DSP is

in the Wait or the Stop mode, and keeping it asserted until

an acknowledge pulse in the DSP is produced, puts the DSP

into the Debug mode. After receiving the acknowledge

pulse, DR must be deasserted before sending the first OnCE

port command. For more information, see Methods Of

Entering The Debug Mode in the DSP56000 Family

Manual.

Note:

If the OnCE port is not in use, an external pull-up resistor

should be attached to the DR line.

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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