MC68HC812A4 Datasheet, PDF (314/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

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17.5 BDM Registers
Seven BDM registers are mapped into the standard 64-Kbyte address
space when BDM is active. The registers can be accessed with the
hardware READ_BD and WRITE_BD commands, but must not be
written during BDM operation. Most users are only interested in the
STATUS register at $FF01; other registers are for use only by BDM
firmware and logic.
The instruction register is discussed for two conditions:
• When a hardware command is executed
• When a firmware command is executed
17.5.1 BDM Instruction Register
This section describes the BDM instruction register under hardware
command and firmware command.
17.5.1.1 Hardware Command
Address: $FF00
Bit 7
6
5
4
3
2
1
Bit 0
Read:
H/F
DATA
R/W BKGND W/B
BD/U
0
0
Write:
Reset: 0
0
0
0
0
0
0
0
Figure 17-4. BDM Instruction Register (INSTRUCTION)
The bits in the BDM instruction register have the following meanings
when a hardware command is executed.
H/F — Hardware/Firmware Flag
1 = Hardware instruction
0 = Firmware instruction
DATA — Data Flag
1 = Data included in command
0 = No data
MC68HC812A4 — Rev. 3.0
314
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