Nexus
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 25-89
Exception conditions that result in data trace synchronization are summarized in Table 25-59., “Data Trace
Exception Summary.”
25.17.5.4 DTM Operation
25.17.5.4.1 Enabling Data Trace Messaging
Data trace messaging can be enabled in one of two ways.
• Setting the DC1[TM] field to enable data trace
• Using the WT[DTS] field to enable data trace on watchpoint hits
Table 25-59. Data Trace Exception Summary
Exception Condition Exception Handling
System Reset Negation At the negation of JTAG reset (JCOMP), queue pointers, counters, state
machines, and registers within the NXDM module are reset. If data trace is
enabled, the first data trace message is a data write/read w/ sync. message.
Data Trace Enabled The first data trace message (after data trace has been enabled) is a
synchronization message.
Exit from Low Power/Debug Upon exit from a low power mode or debug mode the next data trace
message is converted to a data write/read w/ sync. message.
Queue Overrun An error message occurs when a new message cannot be queued due to
the message queue being full. The FIFO discards messages until it has
completely emptied the queue. After it is emptied, an error message is
queued. The error encoding indicates the types of messages that attempted
to be queued while the FIFO was being emptied. The next DTM message in
the queue is a data write/read w/ sync. message.
Periodic Data Trace Synchronization A forced synchronization occurs periodically after 255 data trace messages
have been queued. A data write/read w/ sync. message is queued. The
periodic data trace message counter then resets.
Event In If the nexus module is enabled, an EVTI
assertion initiates a data trace
write/read w/ sync. message upon the next data write/read (if data trace is
enabled and the eic bits of the dc register have enabled this feature).
Attempted Access to Secure Memory Any attempted read or write to secure memory locations temporarily disable
data trace & cause the corresponding DTM to be lost. A subsequent
read/write queues a data trace read/write with sync. message.
Collision Priority All messages have the following priority: Error -> WPM -> DTM. A DTM
message which attempts to enter the queue at the same time as an error
message, or watchpoint message is lost. A subsequent read/write queues a
data trace read/write with sync. message.
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