PXS20RM Datasheet, PDF (1120/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Nexus Crossbar Slave Port Data Trace Module (NXSS) [cut2/3 only]
Table 33-11. Data Trace Size (DSZ) encodings (TCODE = 5, 6, 13, 14)
DTM size encoding
000
001
010
011
100–111
Transfer size
Byte
Halfword (two bytes)
Word (four bytes)
Doubleword (eight bytes)
Reserved
33.6.2 Data Trace
This section deals with the data trace mechanism supported by the NXSS_0 and NXSS_1 modules. Data
trace is implemented via data write messaging (DWM) and data read messaging (DRM).
33.6.3 Data Trace Messaging (DTM)
NXSS_0 and NXSS_1 data trace messaging is accomplished by snooping the NXSS_0 and NXSS_1 data
bus, and storing the information for qualifying accesses (based on enabled features and matching AHB
Master ID and target addresses). The NXSS module traces all data access that meet the selected range and
attributes.
33.6.4 DTM Message Formats
The NXSS module supports five types of DTM Messages — data write, data read, data write
synchronization, data read synchronization, and error messages.
33.6.4.1 Data Write and Data Read Messages
The data write and data read messages contain the data write/read value and the address of the write/read
access, relative to the previous data trace message. Data write message and data read message information
is messaged out in the following format:
5
4
3
2
1
DATA
U-ADDR
DSZ
SRC
TCODE (000101 or 000110)
MSB 1–64 bits
1–32 bits
Max length = 109 bits; Min length = 15 bits
3 bits
4 bits
6 bits
LSB
Figure 33-11. Data Write/Read Message Format
33.6.4.2 DTM Overflow Error Messages
An error message occurs when a new message cannot be queued due to the message queue being full. The
FIFO discards incoming messages until it has completely emptied the queue. After it is emptied, an error
33-12
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor