Datasheet
Chapter 20 S12X Debug (S12XDBGV3) Module
MC9S12XDP512 Data Sheet, Rev. 2.21
746 Freescale Semiconductor
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.
20.1.3 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 either S12XCPU or XGATE buses
— Each comparator features control of R/W and byte/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.
• Three types of breakpoints
— S12XCPU breakpoint entering BDM on breakpoint (BDM)
— S12XCPU breakpoint executing SWI on breakpoint (SWI)
— XGATE breakpoint
• Three trigger modes independent of comparators
— External instruction tagging (associated with S12XCPU instructions only)
— XGATE S/W breakpoint request
— TRIG Immediate software trigger
• Four trace modes
— Normal: change of flow (COF) PC information is stored (see Section 20.4.5.2.1) for change of
flow definition.
— Loop1: same as Normal but inhibits consecutive duplicate source address entries
— Detail: address and data for all cycles except free cycles and opcode fetches are stored
— Pure PC: All program counter addresses are stored.
• 4-stage state sequencer for trace buffer control
— Tracing session trigger linked to Final State of state sequencer
— Begin, End, and Mid alignment of tracing to trigger
20.1.4 Modes of Operation
The S12XDBG module can be used in all MCU functional modes.