Chapter 8 S12X Debug (S12XDBGV3) Module
MC9S12XE-Family Reference Manual , Rev. 1.19
304
Freescale Semiconductor
8.1.2
Overview
The comparators monitor the bus activity of the CPU12X and XGATE. When a match occurs the control
logic can trigger the state sequencer to a new state. On a transition to the Final State, bus tracing is triggered
and/or a breakpoint can be generated.
Independent of comparator matches a transition to Final State with associated tracing and breakpoint can
be triggered by the external TAGHI and TAGLO signals, or by an XGATE module S/W breakpoint request
or by writing to the TRIG control bit.
The trace buffer is visible through a 2-byte window in the register address map and can be read out using
standard 16-bit word reads. Tracing is disabled when the MCU system is secured.
8.1.3
Features
•
Four comparators (A, B, C, and D)
— Comparators A and C compare the full address bus and full 16-bit data bus
— Comparators A and C feature a data bus mask register
— Comparators B and D compare the full address bus only
— Each comparator can be configured to monitor CPU12X or XGATE buses
— Each comparator features selection of read or write access cycles
— Comparators B and D allow selection of byte or word access cycles
— Comparisons can be used as triggers for the state sequencer
•
Three comparator modes
— Simple address/data comparator match mode
— Inside address range mode, Addmin
≤
Address
≤
Addmax
— Outside address range match mode, Address
<
Addmin or Address
>
Addmax
•
Two types of triggers
— Tagged — This triggers just before a specific instruction begins execution
— Force — This triggers on the first instruction boundary after a match occurs.
•
The following types of breakpoints
— CPU12X breakpoint entering BDM on breakpoint (BDM)
— CPU12X breakpoint executing SWI on breakpoint (SWI)
— XGATE breakpoint
WORD
16 bit data entity
Data Line
64 bit data entity
CPU
CPU12X module
Tag
Tags can be attached to XGATE or CPU opcodes as they enter the instruction pipe. If the tagged opcode
reaches the execution stage a tag hit occurs.
Table 8-2. Glossary Of Terms (continued)
Term
Definition
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:
S12XE
products
in
208
MAPBGA
packages