s908qy2ad1vdwer Freescale Semiconductor, Inc, s908qy2ad1vdwer Datasheet - Page 20

• Manufacturer Part Number: s908qy2ad1vdwer
• Description: Mc68hc908qt4a Microcontroller
• 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.
20
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
an input and all other shared modules should be disabled. The ADC does not
override additional modules using the pin.
Pin Name
PTB0
PTB1
PTA0
PTA1
PTA4
PTA5
PTA2
PTA3
(1)
(1)
(1)
(1)
(1)
(1)
Table 1-3. Function Priority in Shared Pins
MC68HC908QYA/QTA Family Data Sheet, Rev. 2
AD0 → TCH0 → KBI0 → PTA0
AD1 → TCH1 → KBI1 → PTA1
IRQ → TCLK → KBI2 → PTA2
RST → KBI3 → PTA3
OSC2 → AD2 → KBI4 → PTA4
OSC1 → AD3 → KBI5 → PTA5
AD4 → PTB0
AD5 → PTB1
DD
or V
Highest-to-Lowest Priority Sequence
SS
NOTE
.
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