mc68hc908lb8 Freescale Semiconductor, Inc, mc68hc908lb8 Datasheet - Page 140

• Manufacturer Part Number: mc68hc908lb8
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Input/Output (I/O) Ports
14.4.3 Port C Input Pullup Enable Register
The port C input pullup enable register (PTCPUE) contains a software configurable pullup device for each
of the seven port C pins. Each bit is individually configurable and requires that the data direction register,
DDRC, bit be configured as an input. Each pullup is automatically and dynamically disabled when a port
bit’s DDRC is configured for output mode.
OSC2EN — Enable PTC1 on OSC2 Pin
PTCPUE2–PTCPUE0 — Port C Input Pullup Enable Bits
140
NOTES:
1. Output does not apply to PTC2.
2. X = Don’t care
3. I/O pin pulled up to V
4. Writing affects data register, but does not affect input.
5. Hi-Z = High impedance
PTCPUE
This read/write bit configures the OSC2 pin function when internal oscillator or RC oscillator option is
selected. this bit has no effect for the XTAL or external oscillator options.
These writable bits are software programmable to enable pullup devices on an input port bit.
Bit
X
1
0
1 = OSC2 pin outputs the internal or RC oscillator clock (BUSCLKX4)
0 = OSC2 pin configured for PTC1 I/O, having all the interrupt and pullup functions
1 = Corresponding port C pin configured to have internal pullup
0 = Corresponding port C pin internal pullup disconnected
Address:
DDRC
Reset:
Read:
Write:
Bit
0
0
1
Figure 14-12. Port C Input Pullup Enable Register (PTCPUE)
DD
OSC2EN
$000E
Bit 7
by internal pullup device.
0
PTC
X
Bit
X
X
(2)
= Unimplemented
6
0
0
Input, Hi-Z
Input, V
Table 14-3. Port C Pin Functions
I/O Pin
Output
Mode
MC68HC908LB8 Data Sheet, Rev. 1
DD
(3)
(5)
5
0
0
DDRC1–DDRC0
DDRC1–DDRC0
DDRC1–DDRC0
4
0
0
Read/Write
Accesses
to DDRC
3
0
0
PTCPUE2
2
0
PTC2–PTC0
Read
Pin
Pin
PTCPUE1
1
0
Accesses
Freescale Semiconductor
to PTC
PTCPUE0
Bit 0
0
PTC1–PTC0
PTC1–PTC0
PTC1–PTC0
Write
(1)
(4)
(4)