Table 1063. Nar Message Formats - STMicroelectronics SPC572L series Reference Manual

RM0400
The NAR generates the following message types:
•
Device_ID—The first message transmitted when the NAR comes up. It consists of a 6-
bit TCODE (TCODE = 1) and the 32-bit device ID. The first beat of the message is
always an IDLE (MSEO = 2b11, MDO = all 0s) to allow the debugger Nexus state
machine to correctly initialize (by moving to end message or idle state). Device_ID is
also generated if the queue is repartitioned (by changing either the ALT or MSP setting
in the NAR_CR) while it is not empty. This serves the dual purpose of insuring that the
user always gets at least one device_ID message and providing a message boundary
in the case where there might have been corruption due to the lost data.
• Watchpoint—The NAR generates its own watchpoint match message under the
following circumstances as shown in
•
NAR_Error (TCODE = 8)—If an error condition is detected inside the NAR, it generates
its own error message. An NAR_Error message consists of the 6-bit TCODE, the 6-bit
NAR source ID, and a 32-bit data field which corresponds to the NAR status register.
An NAR error can be triggered by:
–
–
–
–
This table describes the NAR message formats.
Min
Message
packet
name
size (bits)
6
Device ID 32
0
6
6
Error
4
(1)
Message
12
0
6
Watchpoint
6
Hit
6
(3)
Message
0
1. The Error message conforms to the IEEE-ISTO 5001-2011 standard.
2. Tools should treat the NAR SRC field as a 4-bit SRC field and a 2-bit unused field. The extra 2-bit field (the two most
significant bits of the 6-bit TCODE) is always 0b00. This operation is not compliant to the IEEE-ISTO 5001 Nexus standard.
3. The Watchpoint Hit message does not conform to the IEEE-ISTO 5001-2011 standard, it conforms to the IEEE-ISTO 5001-
2003 standard. The WPHIT should be a variable length packet, but is implemented as a fixed length packet. In most cases,
tools will not see a difference, however, a difference will be seen if a timestamp field is appended to the message.
HBDP error
Illegal configuration
Stall Error
Trace memory bus read/write access error

Table 1063. NAR message formats

Max
Packet
packet
type
size (bits)
6 fixed
32 fixed
24 variable
6 fixed
6 fixed
4 fixed
12 fixed
24 variable
6 fixed
6 fixed
6 fixed
24 variable
DocID027809 Rev 4
Table 1066.
Packet
name
TCODE TCODE value = 1
DID DID register value
TSTAMP Optional, globally synchronized timestamp
TCODE TCODE value = 8
(2)
SRC NAR source ID
ETYPE See Table 1064
ECODE See Table 1065
TSTAMP Optional, globally synchronized timestamp
TCODE Value = 15
2
SRC NAR source ID
WPHIT See Table 1066
TSTAMP Optional, globally synchronized timestamp
Nexus Aurora Router (NAR)
Packet description
1897/2058
1908