Chapter 19 Debug (S12XDBGV2)
MC9S12XDP512 Data Sheet, Rev. 2.17
Freescale Semiconductor
719
19.4.3.4
Trigger On XGATE S/W Breakpoint Request
The XGATE S/W breakpoint request issues a forced breakpoint request to the CPU immediately
independent of DBG settings. If the debug module is armed triggers the state sequencer into the disarmed
state. Active tracing sessions are terminated immediately, thus if tracing has not yet begun using begin-
trigger, no trace information is stored. XGATE generated breakpoints are independent of the DBGBRK
bits. The XGSBPE bit in DBGC1 determines if the XGATE S/W breakpoint function is enabled. The BDM
bit in DBGC1 determines if the XGATE requested breakpoint causes the system to enter BDM mode or
initiate a software interrupt (SWI).
19.4.3.5
Immediate Trigger
At any time independent of comparator matches or external tag signals it is possible to initiate a tracing
session and/or breakpoint by writing to the TRIG bit in DBGC1. This triggers the state sequencer into the
nal state and issues a forced breakpoint request to both CPU and XGATE.
19.4.3.6
Trigger Priorities
In case of simultaneous triggers, the priority is resolved according to
Table 19-38. The lower priority
trigger is suppressed. It is thus possible to miss a lower priority trigger if it occurs simultaneously with a
trigger of a higher priority. The trigger priorities described in
Table 19-38 dictate that in the case of
simultaneous matches, the match on the lower channel number ([0,1,2,3) has priority. The SC[3:0]
encoding ensures that a match leading to nal state has priority over all other matches independent of
current state sequencer state. When congured for range modes a simultaneous match of comparators A
and C generates an active match0 while match2 is suppressed.
Table 19-38. Trigger Priorities
Priority
Source
Action
Highest
XGATE
Immediate forced breakpoint......(Tracing terminated immediately).
TRIG
Enter nal state
External TAGHI/TAGLO
Enter State0
Match0 (force or tag hit)
Trigger to next state as dened by state control registers
Match1 (force or tag hit)
Trigger to next state as dened by state control registers
Match2 (force or tag hit)
Trigger to next state as dened by state control registers
Lowest
Match3 (force or tag hit)
Trigger to next state as dened by state control registers