
General Description
MC68HC908QB8 Data Sheet, Rev. 3
22
Freescale Semiconductor
1.6 Pin Function Priority
Table 1-3 is meant to resolve the priority if multiple functions are enabled on a single pin.
NOTE
Upon reset all pins come up as input ports regardless of the priority table.
PTB4
PTB4 — General-purpose I/O port
Input/Output
RxD — ESCI receive data I/O
Input/Output
AD8 — A/D channel 8 input
Input
PTB5
PTB5 — General-purpose I/O port
Input/Output
TxD — ESCI transmit data I/O
Output
AD9 — A/D channel 9 input
Input
PTB6
PTB6 — General-purpose I/O port
Input/Output
TCH2 — Timer channel 2 I/O
Input/Output
PTB7
PTB7 — General-purpose I/O port
Input/Output
TCH3 — Timer channel 3 I/O
Input/Output
Table 1-3. Function Priority in Shared Pins
Pin Name
Highest-to-Lowest Priority Sequence
PTA0(1)
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.
AD0
→ TCH0 → KBI0 → PTA0
PTA1(1)
AD1
→ TCH1 → KBI1 → PTA1
PTA2
IRQ
→ TCLK → KBI2 → PTA2
PTA3
RST
→ KBI3 → PTA3
PTA4(1)
OSC2
→ AD2 → KBI4 → PTA4
PTA5(1)
OSC1
→ AD3 → KBI5 → PTA5
PTB0(1)
AD4
→ SPSCK → PTB0
PTB1(1)
AD5
→ MOSI → PTB1
PTB2(1)
AD6
→ MISO → PTB2
PTB3(1)
AD7
→ SS → PTB3
PTB4(1)
AD8
→ RxD → PTB4
PTB5(1)
AD9
→ TxD → PTB5
PTB6
TCH2
→ PTB6
PTB7
TCH3
→ PTB7
Table 1-2. Pin Functions (Continued)
Pin
Name
Description
Input/Output