Motorola DSP56000 manual ON-CHIP Emulation Introduction, Debug Serial Input/Chip Status 0 DSI/OS0

ON-CHIP EMULATION INTRODUCTION

10.1ON-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 10-1shows the components of the OnCE circuitry. OnCE is shown as part of the DSP56K central pro- cessing module in Figure 10-2.

PDB PIL GDB

	Pipeline
	Information
XAB	.
	.
YAB
PAB
	PAB
	FIFO

Breakpoint and

Trace Logic

.

Breakpoint

Registers and Comparators

	DSCK/OS1
OnCE	DSI/OS0
Controller
and	DR
Serial
Interface
	DSO

Figure 10-1 OnCE Block Diagram

10.2ON-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

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