SuperH (SH) 64-bit RISC Series SH-5 System Architecture, Volume ...

PRELIMINARY DATA
Debug protocols and interfaces 119
When the SHdebug link is the currently-selected debug interface and SH-5 has no
data to send, the debug module maintains a line idle condition on the SHdebug link.
Message type name Message type field Meaning
MHDR_IDLE 0b000 Line idle condition
MHDR_DBUS 0b001 DBUS message.
MHDR_DTRC_BACK 0b010 DTRC background trace message.
MHDR_DTRC_TRIG 0b011 DTRC trigger trace message.
MHDR_REF 0b100 Reference message
1.9.3 DTRC messages
DTRC messages contain information captured by both the WPC, DM and bus
analyzers.
These are stored in the debug FIFO, or sent to the tool without any CPU
involvement. Such trace messages, sent by the on-chip debug module, include:
• information from each CPU watchpoint hit,
• branch trace information,
• fast printf output,
• information captured in bus analyzer bus capture buffers.
Trace message types
D R A FT
Watchpoints and bus analyzer bus capture buffers can generate two types of trace
message:
• a trigger trace message,
• a background trace message.
0b101, 0b110 or 0b111 Not currently defined
Table 39: Message type values
The watchpoint hit information contained in these two types of message is the same;
the only difference is the use of a different message header code. The use of different
message header codes permits the tool to take different actions for the two types of
trace message.
05-SA-10003 v1.0
SuperH, Inc.
SH-5 System Architecture, Volume 3: Debug