XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 320

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

Development Support
Data Sheet
320
1. STATUS command is a specific case of the READ_BD_BYTE command.
2. ENABLE_FIRMWARE is a specific case of the WRITE_BD_BYTE command.
WRITE_BD_WORD
READ_BD_WORD
WRITE_BD_BYTE
READ_BD_BYTE
BACKGROUND
WRITE_WORD
READ_WORD
FIRMWARE
WRITE_BYTE
READ_BYTE
Command
STATUS
ENABLE_
(1)
(2)
Opcode (Hex)
Hardware commands allow target system memory to be read or written. Target
system memory includes all memory that is accessible by the CPU12 including
on-chip RAM, EEPROM, on-chip I/O and control registers, and external memory
connected to the target HC12 MCU. Hardware commands are implemented in
hardware logic and do not require the HC12 MCU to be in BDM mode for execution.
The control logic watches the CPU12 buses to find a free bus cycle to execute the
command so that the background access does not disturb the running application
programs. If a free cycle is not found within 128 E-clock cycles, the CPU12 is
momentarily frozen so the control logic can steal a cycle. Refer to
commands implemented in BDM control logic.
CC
EC
C4
C4
C8
E4
E4
E0
E8
C0
90
Table 18-2. BDM Hardware Commands
1000 0000 (out)
0000 0000 (out)
1100 0000 (out)
16-bit address
16-bit data out
16-bit address
16-bit address
16-bit data out
16-bit address
16-bit data out
16-bit address
16-bit address
16-bit address
16-bit address
16-bit data out
1xxx xxxx (in)
16-bit data in
16-bit data in
16-bit data in
16-bit data in
FF01,
FF01,
FF01,
FF01,
None
Data
Development Support
Enter background mode (if firmware enabled).
Read from memory with BDM in map (may steal cycles if
external access) data for odd address on low byte, data for even
address on high byte.
READ_BD_BYTE $FF01. Running user code. (BGND
instruction is not allowed.)
READ_BD_BYTE $FF01. BGND instruction is allowed.
READ_BD_BYTE $FF01. Background mode active (waiting for
single wire serial command).
Read from memory with BDM in map (may steal cycles if
external access) must be aligned access.
Read from memory with BDM out of map (may steal cycles if
external access) data for odd address on low byte, data for even
address on high byte.
Read from memory with BDM out of map (may steal cycles if
external access) must be aligned access.
Write to memory with BDM in map (may steal cycles if external
access) data for odd address on low byte, data for even address
on high byte.
Write byte $FF01, set the ENBDM bit. This allows execution of
commands which are implemented in firmware. Typically, read
STATUS, OR in the MSB, write the result back to STATUS.
Write to memory with BDM in map (may steal cycles if external
access) must be aligned access.
Write to memory with BDM out of map (may steal cycles if
external access) data for odd address on low byte, data for even
address on high byte.
Write to memory with BDM out of map (may steal cycles if
external access) must be aligned access.
Description
M68HC12B Family — Rev. 8.0
Table 18-2
MOTOROLA
for