Datasheet

Chapter 8 S12X Debug (S12XDBGV3) Module
MC9S12XE-Family Reference Manual Rev. 1.25
306 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
• External CPU12X instruction tagging trigger independent of comparators
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