MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
25-88 Freescale Semiconductor
25.14.6 Watchpoint Support
The NXDM module provides watchpoint messaging via the auxiliary pins, as defined by IEEE-ISTO
5001-2003.
Watchpoint messages can be generated using the NXDM defined internal watchpoints.
25.14.6.1 Watchpoint Messaging
Enabling watchpoint messaging is accomplished by setting the watchpoint messaging enable bit,
DC1[WEN]. Using the BWC1 and BWC2 registers, two independently controlled internal watchpoints
can be initialized. When a DMA access address matches on BWA1 or BWA2, a watchpoint message will
be transmitted.
The Nexus module provides watchpoint messaging using the TCODE. When either of the two possible
watchpoint sources asserts, a message will be sent to the queue to be messaged out. This message indicates
the watchpoint number.
Figure 25-67. Watchpoint Message Format
25.14.6.2 Watchpoint Error Message
An error message occurs when a new message cannot be queued due to the message queue being full. The
FIFO will discard messages until it has completely emptied the queue. After it is emptied, an error message
will be queued. The error encoding will indicate which types of messages attempted to be queued while
the FIFO was being emptied.
If only a watchpoint message attempts to enter the queue while it is being emptied, the error message will
incorporate the watchpoint only error encoding (00110). If a data trace message also attempts to enter the
queue while it is being emptied, the error message will incorporate error encoding (01000).
Table 25-60. Watchpoint Source Description
Watchpoint Source (4 bits) Watchpoint Description
XXX1 Reserved
XX1X Reserved
X1XX Internal Watchpoint #1 (BWA1 match)
1XXX Internal Watchpoint #2 (BWA2 match)
WPHIT (XXXX)
msb lsb
12
SRC TCODE (001111)
3
6 bits4 bits4 bits
Fixed length = 14 bits
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