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

PRELIMINARY DATA
206 SHdebug link
dm_clkout
dm_osync
dm_out[3:0]
A
B
C
Start and end of messages
Output-idle words are transmitted over the SHdebug link during times when the
debug module has no data to send, for example, when the DM FIFO is empty.
When the FIFO contains several trace messages, they are sent over the SHdebug
link with a minimum of one idle (4-bit) word separating the messages.
Output-idle words serve another purpose; as the means of telling the tool the status
of the debug module DBUS receive buffer. See Section : Flow control of messages
from tool on page 205.
Message structure
A B C
Figure 8: Debug-link output
A B C
output-idle state, DM_OUT[2:0] = 0B000,
DM_OUT[3] = SH-5 DBUS receive buffer busy (1) or empty (0)
start of message, DM_OUT[2:0] = message type
message data
The values signalled on dm_out[2:0] when DM_OSYNC is asserted are defined in First
word of message on page 118.
D R A FT
Table 72 and Table 73 provide some examples of DTRC and DBUS packets as they
appear on the SHdebug link, and give details of the meaning assigned to DM_OUT[3]
during non-idle transmissions.
SuperH, Inc.
SH-5 System Architecture, Volume 3: Debug 05-SA-10003 v1.0