MC908JB12DWE Datasheet, PDF (270/332 Pages) Freescale Semiconductor, Inc – MC68HC908JB16 Technical Data

Input/Output (I/O) Ports
14.4.2 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:
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
Figure 14-6. Data Direction Register C (DDRC)
Bit 0
DDRC0
0
DDRC[1:0] — Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears
DDRC[1:0], 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.
Figure 14-7 shows the port C I/O logic.
READ DDRC ($0006)
WRITE DDRC ($0006)
RESET
WRITE PTC ($0002)
DDRCx
PTCx
PTCx
READ PTC ($0002)
Figure 14-7. Port C I/O Circuit
Technical Data
270
Input/Output (I/O) Ports
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor