MC9S12HY64 Datasheet, PDF (166/792 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Background Debug Module (S12SBDMV1)
When entering background debug mode, the BDM CCR holding register is used to save the condition code
register of the user’s program. It is also used for temporary storage in the standard BDM firmware mode.
The BDM CCR holding register can be written to modify the CCR value.
5.3.2.2 BDM Program Page Index Register (BDMPPR)
Register Global Address 0x3_FF08
7
6
5
4
3
2
R
0
0
0
BPAE
BPP3
BPP2
W
Reset
0
0
0
0
0
0
= Unimplemented, Reserved
Figure 5-5. BDM Program Page Register (BDMPPR)
1
BPP1
0
0
BPP0
0
Read: All modes through BDM operation when not secured
Write: All modes through BDM operation when not secured
Table 5-3. BDMPPR Field Descriptions
Field
7
BPAE
3–0
BPP[3:0]
Description
BDM Program Page Access Enable Bit — BPAE enables program page access for BDM hardware and
firmware read/write instructions The BDM hardware commands used to access the BDM registers (READ_BD
and WRITE_BD) can not be used for global accesses even if the BGAE bit is set.
0 BDM Program Paging disabled
1 BDM Program Paging enabled
BDM Program Page Index Bits 3–0 — These bits define the selected program page. For more detailed
information regarding the program page window scheme, please refer to the S12S_MMC Block Guide.
5.3.3 Family ID Assignment
The family ID is an 8-bit value located in the firmware ROM (at global address: 0x3_FF0F). The read-only
value is a unique family ID which is 0xC2 for devices with an HCS12S core.
5.4 Functional Description
The BDM receives and executes commands from a host via a single wire serial interface. There are two
types of BDM commands: hardware and firmware commands.
Hardware commands are used to read and write target system memory locations and to enter active
background debug mode, see Section 5.4.3, “BDM Hardware Commands”. Target system memory
includes all memory that is accessible by the CPU.
Firmware commands are used to read and write CPU resources and to exit from active background debug
mode, see Section 5.4.4, “Standard BDM Firmware Commands”. The CPU resources referred to are the
accumulator (D), X index register (X), Y index register (Y), stack pointer (SP), and program counter (PC).
Hardware commands can be executed at any time and in any mode excluding a few exceptions as
highlighted (see Section 5.4.3, “BDM Hardware Commands”) and in secure mode (see Section 5.4.1,
MC9S12HY/HA-Family Reference Manual, Rev. 1.04
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