s908qc16vdse Freescale Semiconductor, Inc, s908qc16vdse Datasheet - Page 24

• Manufacturer Part Number: s908qc16vdse
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

General Description
1.6 Pin Function Priority
Table 1-3
1.7 Unused Pin Termination
Input pins and I/O port pins that are not used in the application must be terminated. This prevents excess
current caused by floating inputs, and enhances immunity during noise or transient events. Termination
methods include:
Never connect unused pins directly to V
Since some general-purpose I/O pins are not available on all packages, these pins must be terminated
as well. Either method 1 or 2 above are appropriate.
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1. Configuring unused pins as outputs and driving high or low;
2. Configuring unused pins as inputs and enabling internal pull-ups;
3. Configuring unused pins as inputs and using external pull-up or pull-down resistors.
is meant to resolve the priority if multiple functions are enabled on a single pin.
Upon reset all pins come up as input ports regardless of the priority table.
1. When a pin is to be used as an ADC pin, the I/O port function should be left as
2. T2CH0 and T2CH1 can be repositioned using TIM2POS in CONFIG2
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 4
an input and all other shared modules should be disabled. The ADC does not
override additional modules using the pin.
(see
Pin Name
PTB0
PTB1
PTB2
PTB3
PTB4
PTB5
PTA0
PTA1
PTA4
PTA5
PTB6
PTB7
PTCx
PTDx
PTA2
PTA3
Figure 2-2. Control, Status, and Data
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
Table 1-3. Function Priority in Shared Pins
AD0 → T1CH0 → KBI0 → PTA0
AD1 → T1CH1 → KBI1 → PTA1
IRQ → T1CLK → KBI2 → PTA2
RST → KBI3 → PTA3
OSC2 → AD2 → KBI4 → PTA4
OSC1 → AD3 → KBI5 → PTA5
AD4 → SPSCK → PTB0
AD5 → MOSI → T2CH1
AD6 → MISO → T2CH0
AD7 → SS → T2CLK → PTB3
AD8 → RxD → T2CH0
AD9 → TxD → T2CH1
T1CH2 → PTB6
T1CH3 → PTB7
PTCx
PTDx
DD
or V
Highest-to-Lowest Priority Sequence
SS
NOTE
.
(2)
(2)
Registers).
(2)
(2)
→ PTB5
→ PTB4
→ PTB1
→ PTB2
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