MC68HC812A4 Datasheet, PDF (98/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Bus Control and Input/Output (I/O)
6.4.5 Port C Data Register
Address: $0004
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
Write:
Reset: 0
0
0
0
0
0
0
0
Expanded wide and peripheral: DATA15 DATA14 DATA13 DATA12 DATA11 DATA10 DATA9 DATA8
Expanded narrow: DATA15/7 DATA14/6 DATA13/5 DATA12/4 DATA11/3 DATA10/2 DATA9/1 DATA8/0
Figure 6-5. Port C Data Register (PORTC)
Read: Anytime, if register is in the map
Write: Anytime, if register is in the map
Bits PC7–PC0 correspond to data lines DATA15–DATA8. When this
port is not used for external data such as in single-chip mode, these pins
can be used as general-purpose I/O. DDRC determines the primary
direction for each pin. In narrow expanded modes, DATA15–DATA8 and
DATA7–DATA0 are multiplexed into the MCU through port C pins on
successive cycles. This register is not in the on-chip map in expanded
and peripheral modes.
When the MCU is operating in special expanded narrow mode and port
C and port D are being used for internal visibility, internal accesses
produce full 16-bit information with DATA15–DATA8 on port C and
DATA7–DATA0 on port D. This allows the MCU to operate at full speed
while making 16-bit access information available to external
development equipment in a single cycle. In this narrow mode, normal
16-bit accesses to external memory get split into two successive 8-bit
accesses on port C alone.
MC68HC812A4 — Rev. 3.0
98
Bus Control and Input/Output (I/O)
Advance Information
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