Datasheet

Background Debug Module (BDM)
Operation
MC9S12DP256 — Revision 1.1
Background Debug Module (BDM)
The BDM hardware commands are listed in Table 121.
The READ_BD and WRITE_BD commands allow access to the BDM
register locations. These locations are not normally in the system
memory map but share addresses with the application in memory. To
distinguish between physical memory locations that share the same
address, BDM memory resources are enabled just for the READ_BD
and WRITE_BD access cycle. This allows the BDM to access BDM
locations unobtrusively, even if the addresses conflict with the
application memory map.
Standard BDM
Firmware
Commands
Firmware commands are used to access and manipulate CPU
resources. The system must be in active BDM to execute standard BDM
firmware commands (see Enabling and Activating BDM). Normal
Table 121 Hardware Commands
Command
Opcode
(hex)
Data Description
BACKGROUND 90 None Enter background mode if firmware is enabled.
READ_BD_BYTE E4
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table
in map. Odd address data on low byte; even address data on
high byte
READ_BD_WORD EC
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table
in map
. Must be aligned access.
READ_BYTE E0
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table
out of map. Odd address data on low byte; even address data
on high byte
READ_WORD E8
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table
out of map. Must be aligned access.
WRITE_BD_BYTE C4
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table in
map. Odd address data on low byte; even address data on
high byte
WRITE_BD_WORD CC
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table in
map. Must be aligned access
WRITE_BYTE C0
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table out
of map. Odd address data on low byte; even address data on
high byte
WRITE_WORD C8
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table out
of map. Must be aligned access.
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Freescale Semiconductor, Inc.
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