Motorola 24-Bit Digital Signal Processor, DSP56000 - page 196

ON-CHIP EMULATION INTRODUCTION
10- 4 ON-CHIP EMULATION (OnCE) MOTOROLA
10.1 ON-CHIP EMULATION INTRODUCTION
The DSP56K on-chip emulation (OnCE) circuitry provides a sophisticated debugging tool
that allows simple, inexpensive, and speed independent access to the processor’s inter-
nal registers and peripherals. OnCE tells application programmers exactly what the status
is within the registers, memory locations, buses, and even the last five instructions that
were executed. OnCE capabilities are accessible through a standard set of pins which are
the same on all of the members of the DSP56K processor family. Figure 10-1 shows the
components of the OnCE circuitry. OnCE is shown as part of the DSP56K central pro-
cessing module in Figure 10-2.
10.2 ON-CHIP EMULATION (OnCE) PINS
The following paragraphs describe the OnCE pins associated with the OnCE controller
and serial interface component shown in Figure 10-1.
10.2.1 Debug Serial Input/Chip Status 0 (DSI/OS0)
Serial data or commands are provided to the OnCE controller through the DSI/OS0 pin
when it is an input. The data received on the DSI pin will be recognized only when the
DSP56K has entered the debug mode of operation. Data is latched on the falling edge of
the DSCK serial clock (described in Section 10.2.2). Data is always shifted into the OnCE
serial port most significant bit (MSB) first. When the DSI/OS0 pin is an output, it works in
conjunction with the OS1 pin to provide chip status information (see Table 10-1). The
PAB
FIFO Breakpoint Registers
and
Comparators
Pipeline
Information Breakpoint and
Trace Logic
OnCE
Controller
and
Serial
Interface
PAB
YAB
XAB ..
PDB PIL GDB
DSO
DR
DSI/OS0
DSCK/OS1
.
Figure 10-1 OnCE Block Diagram