dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 316

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

JTAG and Enhanced On-Chip Emulation (Enhanced OnCE)
11.3
Resources in the Enhanced OnCE module can be accessed either through the JTAG port or under software
program control from the DSC core. These two methods allow debugging activity to be controlled either
by a host development system or by a program that is executing on the DSP56800E device. The two
methods are discussed below.
11.3.1
Development and debugging systems can control Enhanced OnCE debugging actions by communicating
with the Enhanced OnCE via the JTAG port. All of the Enhanced OnCE resources are available serially
through the normal JTAG access protocol.
When interacting via JTAG, the DSP56800E JTAG and Enhanced OnCE modules are tightly coupled. The
interface for both modules is handled by the JTAG port, which communicates with the host software
development and debug systems. Figure 11-2 shows a block diagram of the JTAG/Enhanced OnCE
modules and the JTAG terminals used in the external interface.
The JTAG acts as an external interface controller for the Enhanced OnCE, transparently passing all
communication between the Enhanced OnCE and the host development system. The JTAG port enables
interaction with the debug capabilities provided by the Enhanced OnCE, and its external serial interface is
used by the Enhanced OnCE module for sending and receiving debugging commands and data.
A special JTAG instruction is executed to enable communication with the Enhanced OnCE module. While
Enhanced OnCE communication is active, the JTAG module transparently transfers all data that is
received on the JTAG port to the Enhanced OnCE module.
The JTAG port can also act as a completely independent module. When it is disabled, it has no impact on
the function of the core.
11-4
Accessing the Enhanced OnCE Module
External Interaction via JTAG
The Enhanced OnCE blocks shown in Figure 11-1 (EOnCE Control,
Breakpoint Unit, and Trace Buffer) are actually located inside the
DSP56800E core. The figure is only conceptual and was drawn this way
to better demonstrate how these individual blocks are used in a
DSP56800E system.
DSP56800E Core Reference Manual
NOTE:
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