4 port c, 1 port c data register, 2 data direction register c – Freescale Semiconductor MC68HC908MR32 User Manual
Page 106: Port c, Port c data register, Data direction register c
Input/Output (I/O) Ports (PORTS)
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
106
Freescale Semiconductor
10.4 Port C
Port C is a 7-bit, general-purpose, bidirectional I/O port that shares two of its pins with the analog-to-digital
convertor module (ADC).
10.4.1 Port C Data Register
The port C data register (PTC) contains a data latch for each of the seven port C pins.
PTC[6:0] — 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.
10.4.2 Data Direction Register C
Data direction register C (DDRC) determines whether each port C pin is an input or an output. Writing a
logic 1 to a DDRC bit enables the output buffer for the corresponding port C pin; a logic 0 disables the
output buffer.
DDRC[6:0] — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears DDRC[6:0], 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.
Address:
$0002
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Write:
R
Reset:
Unaffected by reset
R
= Reserved
Figure 10-8. Port C Data Register (PTC)
Address:
$0006
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
Write:
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 10-9. Data Direction Register C (DDRC)