Figure 10-2 Once Module Multiprocessor Configuration; Once Controller - Motorola DSP56309 User Manual

On-Chip Emulation Module
Debug Event (DE)
10.3 DEBUG EVENT (DE)
The bidirectional open drain debug event signal (DE) provides a fast means of entering
debug mode from an external command controller (when input), and a fast means of
acknowledging the entering of debug mode to an external command controller (when
output). The assertion of this signal by a command controller causes the DSP56300 core
to finish the current instruction being executed, save the instruction pipeline
information, enter debug mode, and wait for commands to be entered from the TDI line.
If the DE signal is used to enter debug mode, then it must be deasserted after the OnCE
port responds with an acknowledge and before sending the first OnCE command. The
assertion of this signal by the DSP56300 core indicates that the DSP has entered debug
mode and is waiting for commands to be entered from the TDI line. The DE signal also
facilitates multiple processor connections, as shown in Figure 10-2.
DE
TDI
TDI
TMS
TCK
TRST

Figure 10-2 OnCE Module Multiprocessor Configuration

In this way, the user can stop all the devices in the system when one of the devices enters
debug mode. The user can also stop all the devices synchronously by asserting the DE
line.
10.4

OnCE CONTROLLER

The OnCE controller contains the following blocks: OnCE Command Register (OCR),
OnCE Decoder, and the status/control register. Figure 10-3 illustrates a block diagram
of the OnCE controller.
10-4
TDO
TDI
DSP56309UM/D
TDO
TDI TDO
TDO
AA0703
MOTOROLA