MC68HC812A4 Datasheet, PDF (315/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Development Support
BDM Registers
R/W — Read/Write Flag
0 = Write
1 = Read
BKGND — Hardware Request Bit to Enter Active Background Mode
1 = Hardware background command (INSTRUCTION = $90)
0 = Not a hardware background command
W/B — Word/Byte Transfer Flag
1 = Word transfer
0 = Byte transfer
BD/U — BDM Map/User Map Flag
Indicates whether BDM registers and ROM are mapped to addresses
$FF00 to $FFFF in the standard 64-Kbyte address space. Used only
by hardware read/write commands.
1 = BDM resources in map
0 = BDM resources not in map
17.5.1.2 Firmware Command
Address: $FF00
Bit 7
6
5
4
3
2
1
Bit 0
Read:
H/F
DATA
R/W
Write:
TTAGO
REGN
Reset: 0
0
0
0
0
0
0
0
Figure 17-5. BDM Instruction Register (INSTRUCTION)
The bits in the BDM instruction register have the following meanings
when a firmware command is executed.
H/F — Hardware/Firmware Flag
1 = Hardware control logic
0 = Firmware control logic
DATA — Data Flag
1 = Data included in command
0 = No data
Advance Information
MOTOROLA
Development Support
MC68HC812A4 — Rev. 3.0
315