Figure 10-1 Once Module Block Diagram; Introduction; Once Module Signals - Motorola DSP56309 User Manual

10.1

INTRODUCTION

The DSP56300 core On-Chip Emulation (OnCEª) module provides a means of
interacting with the DSP56300 core and its peripherals nonintrusively so that a user can
examine registers, memory, or on-chip peripherals, thus facilitating hardware and
software development on the DSP56300 core processor. To achieve this, 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. These resources are accessible even
when the chip is operating in normal mode. See Section 11ÑJTAG Port for a description
of the JTAG functionality and its relation to the OnCE module. Figure 10-1 shows the
block diagram of the OnCE module.
PDB PIL GDB
Pipeline
Information
XAB
YAB
PAB
Trace
Buffer
10.2

OnCE MODULE SIGNALS

The OnCE module controller functionality is accessed through the JTAG port. There are
no dedicated OnCE module signals for the clock, data in, or data out. The JTAG signals
TCK, TDI, and TDO are used to shift in and out data and instructions. See
Section 11.2ÑJTAG Signals on page 11-4 for the description of the JTAG signals. To
facilitate emulation-specific functions, one additional signal, called DE, is provided on
the DSP56309.
MOTOROLA
Control Bus
Breakpoint
Tags
Buffer

Figure 10-1 OnCE Module Block Diagram

DSP56309UM/D
Trace Logic
OnCE
Controller
Logic
On-Chip Emulation Module
Introduction
TCK
TDI
TDO
TRST
DE
AA0702
10-3