10.11 Target Site Debug System Requirements; 10.12 Once Module Examples - Motorola DSP56309 User Manual

on the DE line indicating that the chip has entered debug mode. Optionally the external
command controller can poll the OS1 and OS0 bits in the JTAG instruction shift register.
The external command controller communicates with the chip by sending 8-bit
commands that can be accompanied by 24 bits of data. Both commands and data are sent
or received LSB first. After sending a command, the external command controller should
wait for the DSP56300 core chip to acknowledge execution of the command. The external
command controller can send a new command only after the chip has acknowledged
execution of the previous command.
The OnCE commands are classified as follows:
¥ Read commands (when the chip delivers the required data)
¥ Write commands (when the chip receives data and writes the data in one of the
OnCE registers)
¥ Commands that do not have data transfers associated with them
The commands are 8 bits long. The command formats are shown in Figure 10-4
on page 10-5.

10.11 TARGET SITE DEBUG SYSTEM REQUIREMENTS

A typical debug environment consists of a target system where the DSP56300 core-based
device resides in the user defined hardware. The JTAG port interfaces to the external
command controller over a 8-wire link consisting of the five JTAG port wires, one OnCE
module wire, a ground, and a reset wire. The reset wire is optional and is only used to
reset the DSP56300 core-based device and its associated circuitry.
The external command controller acts as the medium between the DSP56300 core target
system and a host computer. The external command controller circuit acts as a JTAG
port driver and host computer command interpreter. The controller issues commands
based on the host computer inputs from a user interface program that communicates
with the user.

10.12 OnCE MODULE EXAMPLES

Following are some examples of debugging procedures. All these examples assume that
the DSP is the only device in the JTAG chain. If there is more than one device in the chain
(additional DSPs or other devices), the other devices can be forced to execute the JTAG
BYPASS instruction such as their effect in the serial stream will be one bit per additional
MOTOROLA
Target Site Debug System Requirements
DSP56309UM/D
On-Chip Emulation Module
10-23