
MOTOROLA
Chapter 23. READI Module
23-33
Pin Interface
The maximum message length is 94 bits. The maximum number of fields is 3, excluding
the TCODE itself.
The double edges in
Table 23-22 indicate the required MSEO/MSEI assertion or negation
indicating the start of message or end of message respectively.
The shaded edges in
Table 23-22 indicate how information can be packed into super-fields
delimited via MSEO/MSEI assertion followed by MSEO/MSEI negation.
23.3.2.5 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 eight, 16, 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 23-14 shows the transmission sequence of a message which
is made up of a TCODE, a variable length field, and finally a super-field consisting
of a fixed length and a variable length field. The only exception to this rule is the dev
Program Trace —
Direct Branch
Synchronization
Message With
Compressed Code
60
(0x3C)
Fixed = 6
Variable
Max = 23
Min = 1
NA
35 bits
13 bits
Program Trace—
Indirect Branch
Synchronization
Message With
Compressed Code
61
(0x3D)
Fixed = 6
Variable
Max = 23
Min = 1
NA
35 bits
13 bits
1 Maximum information size. The actual number of bits transmitted is dependant on the number of MDO
pins.
2 Minimum information size. The actual number of bits transmitted is dependent on the number of MDO
pins.
Table 23-22. Message Field Sizes (continued)
Message
TCODE
Field # 1
Field # 2
Field # 3
Max
Size 1
Min.
Size 2