Motorola DSP56305, User Manual

Page: 379 / 664

On-Chip Emulation Module
Introduction
MOTOROLA DSP56305 User’s Manual 10-3
10.1 INTRODUCTION
The DSP56300 core On-Chip Emulation (OnCE™) module provides a means of
unintrusive interaction with the DSP56300 core and its peripherals. The OnCE module
allows the user to examine registers, memory, or on-chip peripherals, thus facilitating
hardware and software development on the DSP56300 core processor. Special circuits
and dedicated signals on the DSP56300 core are defined to avoid sacrificing any
user-accessible on-chip resource. The OnCE module resources can be accessed only after
executing the JTAG instruction ENABLE_ONCE. See Section 11, JTAG Port, for a
description of the JTAG functionality and its relation to the OnCE. Figure 10-1 shows the
block diagram of the OnCE module.
10.2 OnCE MODULE SIGNALS
The OnCE module controller functionality is accessed through the JTAG Test Access
Port (TAP). There are no dedicated OnCE module signals for clock, data in, or data out.
The JTAG signals TCK, TDI, and TDO are used to shift data and instructions in and out.
See JTAG Signals on page 11-5 for the description of the JTAG signals. To facilitate
emulation-specific functions, one additional signal, called DE, is provided on the
DSP56305.
Figure 10-1 OnCE Module Block Diagram
Trace
Buffer
Breakpoint
Logic
Pipeline
Information
Trace Logic
OnCE
Controller
PAB
YAB
XAB
PDB PIL GDB
TDO
TRST
TDI
TCK
Tags
Buffer
Control Bus
DE
AA0702