
MOTOROLA
Chapter 24. READI Module
24-23
Signal Interface
.
Figure 24-11. Functional Diagram of Signal Interface
The signal interface is responsible for handshaking with the message queue and registers.
It is also responsible for requesting new messages from the message queue. A message is
always requested from the message queue if the message queue is not empty, the message
buffer is available and a higher priority message is not requesting to be transmitted. The
rate at which data is removed from the queue depends on the average message length, the
number of MDO signals, and the MCKO clocking rate.
24.7.3
Message Priority
Message formatting is performed in the signal interface block. The following priority
scheme is implemented for messages sent to the signal output formatter block, with 1 being
the highest priority and 5 being the lowest priority:
1. Invalid message
2. READI register access handshakes (device ready/download information)
3. Watchpoint messages
4. Read/write access message
5. RCPU development access message
6. Queued messages (program trace, data trace, and ownership trace)
Control Unit
Signal Interface
Trace messages from Queue
Data to READI
Output Formatter
Input Formatter
MDO[7:0]
MDI[1:0]
MCK
O
M
SEO
M
SEI
MCK
I
RSTI
EVTI
MUX
BUF
Auxiliary messages
Watchpoint message
RCPU Dev. Port message
Data
Control
Invalid Message
R/W Access message
Registers