MC908AS60ACFU Datasheet, PDF (254/414 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Input/Output Ports
22.4 Port C
Port C is an 6-bit general-purpose bidirectional I/O port. Note that PTC5 is only available on 64-pin
package options.
22.4.1 Port C Data Register
The port C data register contains a data latch for each of the six port C pins.
Address:
Read:
Write:
Reset:
Alternative
Functions:
$0002
Bit 7
0
R
R
6
5
0
PTC5
R
= Reserved
4
3
PTC4
PTC3
Unaffected by Reset
2
PTC2
MCLK
Figure 22-8. Port C Data Register (PTC)
1
PTC1
Bit 0
PTC0
PTC[5:0] — 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 (5:0).
MCLK — System Clock Bit
The system clock is driven out of PTC2 when enabled by MCLKEN bit in PTCDDR7.
22.4.2 Data Direction Register C
Data direction register C 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.
Address: $0006
Bit 7
6
Read:
0
MCLKEN
Write:
R
5
DDRC5
4
DDRC4
3
DDRC3
2
DDRC2
1
DDRC1
Reset: 0
0
0
0
0
0
0
R
= Reserved
Figure 22-9. 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, DDRC2 has no
effect. Reset clears this bit.
1 = MCLK output enabled
0 = MCLK output disabled
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
254
Freescale Semiconductor