MMC2107 - Freescale Semiconductor

Freescale Semiconductor, Inc.
JTAG Test Access Port and OnCE
Functional Description
Address comparators can be used to determine where a program may
be getting lost or when data is being written to areas which should not
be written. They are also useful in halting a program at a specific point
to examine or change registers or memory. Using address comparators
to set breakpoints enables the user to set breakpoints in RAM or ROM
in any operating mode. Memory accesses are monitored according to
the contents of the OCR.
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Freescale Semiconductor, I
21.14.6.1 Memory Address Latch (MAL)
21.14.6.2 Breakpoint Address Base Registers
The address comparator generates a match signal when the address on
the bus matches the address stored in the breakpoint address base
register, as masked with individual bit masking capability provided by the
breakpoint address mask register. The address match signal and the
access attributes are further qualified with the RCx4–RCx0 and
BCx4–BCx0 control bits. This qualification is used to decrement the
breakpoint counter conditionally if its contents are non-zero. If the
contents are zero, the counter is not decremented and the breakpoint
event occurs (ISBKPTx asserted).
The MAL is a 32-bit register that latches the address bus on every
access.
The 32-bit breakpoint address base registers (BABA and BABB) store
memory breakpoint base addresses. BABA and BABB can be read or
written through the OnCE serial interface. Before enabling breakpoints,
the external command controller should load these registers.
21.14.7 Breakpoint Address Mask Registers
The 32-bit breakpoint address mask registers (BAMA and BAMB)
registers store memory breakpoint base address masks. BAMA and
BAMB can be read or written through the OnCE serial interface. Before
enabling breakpoints, the external command controller should load
these registers.
MMC2107 – Rev. 2.0
Technical Data
MOTOROLA JTAG Test Access Port and OnCE 571
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