
READI Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
24-31
The maximum message length is 94 bits. The maximum number of fields is three, excluding the TCODE
itself.
24.7.5.2
Rules of Messages
A variable sized field within a message must end on a port boundary.
A variable sized field may start within a port boundary only when following a fixed length packet.
Super fields must end on a port boundary (2-, 4-, or 8-bit boundaries depending on whether the
device receives or sends messages, and the port size configured).
When a variable length field is sized such that it does not end on a port boundary, it is necessary to
extend and zero fill the remaining bits after the highest-order bit so that it can end on a port
boundary.
A data field within a data trace message must be 8, 16, 24, or 32 bits in length.
The field containing the TCODE number is always transferred out first, followed by subsequent fields of
information. Within a field, the lowest significant bits are shifted out first.
Figure 24-14 shows the
transmission sequence of a message which is made up of a TCODE (a fixed-length field) and a variable
length field (FIELD 1), together making a super field. Every instance of a fixed length field followed by
a variable field is a super field.
Figure 24-14, for example, shows two super fields. The only exception to
Program Trace —
Direct Branch
Synchronization
Message With
Compressed Code (PTSM = 1) 5
60
(0x3C)
Variable
Max = 8
Min = 1
Fixed = 6
Variable
Min = 1
Max = 23
43 bits
14 bits
Program Trace—
Indirect Branch
Synchronization
Message With
Compressed Code (PTSM = 0) 5
61
(0x3D)
Fixed = 6
Variable
Max = 23
Min = 1
NA
35 bits
13 bits
Program Trace—
Indirect Branch
Synchronization
Message With
Compressed Code (PTSM = 1) 5
61
(0x3D)
Variable
Max = 8
Min = 1
Fixed = 6
Variable
Min = 1
Max = 23
43 bits
14 bits
1 The double edges indicate that MSEO/MSEI is asserted to indicate the start of a message or negated to indicate the
2 The shaded edges indicate super fields that can hold information delimited via MSEO/MSEI assertion followed by
MSEO/MSEI negation.
3 Maximum information size. The actual number of bits transmitted is dependant on the number of MDO signals.
4 Minimum information size. The actual number of bits transmitted is dependent on the number of MDO signals.
6 Not available prior to Rev. D of the MPC561 and is not available in Rev. B and earlier versions of the MPC563
7 Only available on MPC562/MPC564
Table 24-22. Message Field Sizes1,2 (continued)
Message
TCODE
Field # 1
Field # 2
Field # 3
Max
Size3
Min.
Size4