S908QC16CDRE FREESCALE [Freescale Semiconductor, Inc], S908QC16CDRE Datasheet - Page 113

• Manufacturer Part Number: S908QC16CDRE
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

DDRC[2:0] — Data Direction Register C Bits
When DDRCx is a 1, reading address $0001 reads the PTCx data latch. When DDRCx is a 0, reading
address $0002 reads the voltage level on the pin. The data latch can always be written, regardless of the
state of its data direction bit.
11.5.3 Port C Input Pullup Enable Register
The port C input pullup enable register (PTCPUE) contains a software configurable pullup device for each
of the four port C pins. Each bit is individually configurable and requires the corresponding data direction
register, DDRCx, be configured as input. Each pullup device is automatically and dynamically disabled
when its corresponding DDRCx bit is configured as output.
Freescale Semiconductor
These read/write bits control port C data direction. Reset clears DDRC[2:0], configuring all port C pins
as inputs.
1 = Corresponding port C pin configured as output
0 = Corresponding port C pin configured as input
Reset:
Read:
Write:
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.
port C I/O logic.
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 2
Figure 11-12. Port C Input Pullup Enable Register (PTCPUE)
READ DDRC ($0006)
WRITE DDRC ($0006)
WRITE PTC ($0002)
READ PTC ($0002)
Bit 7
0
0
= Unimplemented
6
0
0
Figure 11-11
RESET
Figure 11-11. Port C I/O Circuit
5
0
0
does not apply to PTC3.
DDRCx
NOTE
NOTE
PTCx
4
0
0
PTCPUE3 PTCPUE2 PTCPUE1 PTCPUE0
3
0
Figure 11-11
2
0
PTCPUEx
1
0
shows the
PULLUP
Bit 0
PTCx
0
Port C
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