MC68HC908EY16 Datasheet, PDF (119/278 Pages) Motorola, Inc – Microcontrollers

Port C
12.4 Port C
Port C is an 5-bit general-purpose bidirectional I/O port that shares pin functions with the internal clock
generator (ICG) and serial peripheral interface (SPI) modules.
12.4.1 Port C Data Register
The port C data register contains a data latch for each of the five port C pins.
Address: $0002
Bit 7
6
Read: 0
0
Write:
Reset:
Alternative Function:
5
4
3
2
1
Bit 0
0
PTC4
PTC3
PTC2
PTC1
PTC0
Unaffected by reset
OSC1 OSC2
MCLK
MOSI
MISO
= Unimplemented
Figure 12-7. Port C Data Register (PTC)
PTC[4:0] — 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.
MCLK — T12 System Clock Bit
The system clock is driven out of PTC2 when enabled by MCLKEN bit in PTCDDR7.
12.4.2 Data Direction Register C
Data direction register C 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: $0006
Bit 7
6
5
4
3
2
1
Read:
0
MCLKEN
Write:
0
DDRC4 DDRC3 DDRC2 DDRC1
Reset: 0
0
0
0
0
0
0
= Unimplemented
Figure 12-8. Data Direction Register C (DDRC)
Bit 0
DDRC0
0
MCLKEN — MCLK Enable Bit
This read/write bit enables MCLK to be an output signal on PTC2. If MCLK is enabled, PTC2 is under
the control of MCLKEN. Reset clears this bit.
1 = MCLK output enabled
0 = MCLK output disabled
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
Freescale Semiconductor
119