mc9s12xs128 Freescale Semiconductor, Inc, mc9s12xs128 Datasheet - Page 179

• Manufacturer Part Number: mc9s12xs128
• Description: Hcs12 Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

1
2
3
5.4.5
Hardware and firmware BDM commands start with an 8-bit opcode followed by a 16-bit address and/or a
16-bit data word depending on the command. All the read commands return 16 bits of data despite the byte
or word implication in the command name.
Freescale Semiconductor
READ_NEXT
READ_PC
READ_D
READ_X
READ_Y
READ_SP
WRITE_NEXT<f-
helvetica><st-
superscript>
WRITE_PC
WRITE_D
WRITE_X
WRITE_Y
WRITE_SP
GO
GO_UNTIL
TRACE1
TAGGO -> GO
If enabled, ACK will occur when data is ready for transmission for all BDM READ commands and will occur after the write is
complete for all BDM WRITE commands.
are accessed rather than user code. Writing BDM firmware is not possible.
System stop disables the ACK function and ignored commands will not have an ACK-pulse (e.g., CPU in stop or wait mode).
The GO_UNTIL command will not get an Acknowledge if CPU executes the wait or stop instruction before the “UNTIL”
condition (BDM active again) is reached (see
When the firmware command READ_NEXT or WRITE_NEXT is used to access the BDM address space the BDM resources
Command
3
2
BDM Command Structure
1
8-bit reads return 16-bits of data, of which, only one byte will contain valid
data. If reading an even address, the valid data will appear in the MSB. If
reading an odd address, the valid data will appear in the LSB.
Opcode
(hex)
0C
62
63
64
65
66
67
42
43
44
45
46
47
08
10
18
16-bit data out Increment X index register by 2 (X = X + 2), then read word X points to.
16-bit data out Read program counter.
16-bit data out Read D accumulator.
16-bit data out Read X index register.
16-bit data out Read Y index register.
16-bit data out Read stack pointer.
16-bit data in
16-bit data in
16-bit data in
16-bit data in
16-bit data in
16-bit data in
Data
none
none
none
none
S12XS Family Reference Manual, Rev. 1.10
Table 5-7. Firmware Commands
Section 5.4.7, “Serial Interface Hardware Handshake Protocol”
Increment X index register by 2 (X = X + 2), then write word to location
pointed to by X.
Write program counter.
Write D accumulator.
Write X index register.
Write Y index register.
Write stack pointer.
Go to user program. If enabled, ACK will occur when leaving active
background mode.
Go to user program. If enabled, ACK will occur upon returning to active
background mode.
Execute one user instruction then return to active BDM. If enabled,
ACK will occur upon returning to active background mode.
(Previous enable tagging and go to user program.)
This command will be deprecated and should not be used anymore.
Opcode will be executed as a GO command.
Description
Background Debug Module (S12XBDMV2)
last Note).
179