Chapter 6 S12Z Debug (S12ZDBGV2) Module
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
Freescale Semiconductor
223
shows the profiling clock, PDOCLK, whose edges are offset from the bus clock, to ease setup
and hold time requirements relative to PDO, which is synchronous to the bus clock.
Figure 6-31. PDO Profiling Clock Control
The trace buffer is used as a temporary storage medium to store COF information before it is transmitted.
COF information can be transmitted whilst new information is written to the trace buffer. The trace buffer
data is transmitted at PDO least significant bit first. After the first trace buffer entry is made, transmission
begins in the first clock period in which no further data is written to the trace buffer.
If a trace buffer line transmission completes before the next trace buffer line is ready, then the clock output
is held at a constant level until the line is ready for transfer.
6.4.6.2
Profiling Configuration, Alignment and Mode Dependencies
The PROFILE bit must be set and the DBG armed to enable profiling. Furthermore the PDOE bit must be
set to configure the PDO and PDOCLK pins for profiling.
If TALIGN is configured for End-Aligned tracing then profiling begins as soon as the module is armed.
If TALIGN is configured for Begin-aligned tracing, then profiling begins when the state sequencer enters
Final State and continues until a software disarm or trace buffer overflow occurs; thus profiling does not
terminate after 64 line entries have been made.
Mid-Align tracing is not supported whilst profiling; if the TALIGN bits are configured for Mid-Align
tracing when PROFILE is set, then the alignment defaults to end alignment.
Profiling entries continue until either a trace buffer overflow occurs or the DBG is disarmed by a state
machine transition to State0. The profiling output transmission continues, even after disarming, until all
trace buffer entries have been transmitted. The PTACT bit indicates if a profiling transmission is still
active. The PTBOVF indicates if a trace buffer overflow has occurred.
The profiling timestamp feature is used only for the PTVB and PTW formats, thus differing from
timestamps offered in other modes.
Profiling does not support trace buffer gating. The external pin gating feature is ignored during profiling.
When the DBG module is disarmed but profiling transmission is ongoing, register write accesses are
suppressed.
When the DBG module is disarmed but profiling transmission is still ongoing, reading from the DBGTB
returns the code 0xEE.
BUS CLOCK
PDO
STROBE
CLOCK ENABLE
PDOCLK
