PXS20RM Datasheet, PDF (1122/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Nexus Crossbar Slave Port Data Trace Module (NXSS) [cut2/3 only]
5
4
3
2
1
DATA
F-ADDR
DSZ
SRC
TCODE (001101 or 001110)
MSB 1–64 bits
1–32 bits
Max length = 109 bits; Min length = 15 bits
3 bits
4 bits
6 bits
LSB
Figure 33-13. Data Write/Read w/ Sync Message Format
Exception conditions that result in data trace synchronization are summarized in Table 33-12.
Table 33-12. 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 NXSS_0 and NXSS_1 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 Debug
Upon exit from 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.
33.6.5 DTM operation
33.6.5.1 Enabling data trace messaging
Data trace messaging can be enabled in one of two ways.
• Setting the DC1[TM] field to enable data trace
33-14
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor