MC68HC908GR16 Datasheet, PDF (128/276 Pages) Motorola, Inc – Microcontrollers

Input/Output Ports (PORTS)
12.4 Port C
Port C is a 7-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 port C pins.
Address:
Read:
Write:
Reset:
$0002
Bit 7
0
6
5
4
3
2
PTC6
PTC5
PTC4
PTC3
PTC2
Unaffected by reset
= Unimplemented
R = Reserved
Figure 12-9. Port C Data Register (PTC)
1
PTC1
Bit 0
PTC0
PTC6 and 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.
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
0
6
DDRC6
5
DDRC5
4
DDRC4
3
DDRC3
2
DDRC2
1
DDRC1
0
0
0
0
0
0
0
= Unimplemented
Figure 12-10. Data Direction Register C (DDRC)
Bit 0
DDRC0
0
DDRC6 and DDRC0 — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears DDRC6 and 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.
Figure 12-11 shows the port C I/O logic.
MC68HC908GR16 Data Sheet, Rev. 5.0
128
Freescale Semiconductor