MC68HC908GR8A_07 Datasheet, PDF (122/260 Pages) Freescale Semiconductor, Inc – Microcontrollers

Input/Output (I/O) Ports
12.4 Port C
Port C is a 2-bit, general-purpose bidirectional I/O port. Port C also has software configurable pullup
devices if configured as an input port.
12.4.1 Port C Data Register
The port C data register (PTC) contains a data latch for each of the two port C pins.
Address: $0002
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
0
0
0
0
0
PTC1
PTC0
Write:
Reset:
Unaffected by reset
= Unimplemented
Figure 12-9. Port C Data Register (PTC)
PTC1–PTC0 — Port C Data Bits
These read/write bits are software-programmable. Data direction of each port C pin is under the control
of the corresponding bit in data direction register C. Reset has no effect on port C data.
NOTE
PTC is not available in a 28-pin DIP or SOIC package.
12.4.2 Data Direction Register C
Data direction register C (DDRC) determines whether each port C pin is an input or an output. Writing a 1
to a DDRC bit enables the output buffer for the corresponding port C pin; a 0 disables the output buffer.
Address:
Read:
Write:
Reset:
$0006
Bit 7
6
5
4
3
2
1
0
0
0
0
0
0
DDRC1
0
0
0
0
0
0
0
= Unimplemented
Figure 12-10. Data Direction Register C (DDRC)
Bit 0
DDRC0
0
DDRC1–DDRC0 — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears DDRC1–DDRC0, configuring all port
C pins as inputs.
1 = Corresponding port C pin configured as output
0 = Corresponding port C pin configured as input
NOTE
Avoid glitches on port C pins by writing to the port C data register before
changing data direction register C bits from 0 to 1.
For those devices packaged in a 28-pin DIP or SOIC package,
PTC1–PTC0 are not connected. Set DDRC1 and DDRC0 to a 1 to
configure PTC1–PTC0 as outputs.
MC68HC908GR8A • MC68HC908GR4A Data Sheet, Rev. 5
122
Freescale Semiconductor