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Reading PDRB always gives the pin states. However, if a port B pin is selected as an analog input
channel for the A/D converter by AMR bits CH3 to CH0, that pin reads 0 regardless of the input
voltage.
Port Mode Register B (PMRB)
Bit
Initial value
Read/Write
PMRB is an 8-bit read/write register controlling the selection of the PB
PMRB is initialized to H'F7.
Bits 7 to 4 and 2 to 0—Reserved
Bits 7 to 4 and 2 to 0 are reserved; they are always read as 1 and cannot be modified.
IRQ
IRQ
IRQ
Bit 3—PB
/AN
/IRQ
3
3
These bits select whether pin PB
Bit 3
IRQ1
Description
0
Functions as PB
Functions as IRQ
1
Note: Rising or falling edge sensing can be selected for the IRQ
For TMIC pin setting information, see the Timer More Register C (TMC) description in section
9.3.2, Register Descriptions.
7
6
5
1
1
1
Pin Function Switch (IRQ1)
1
/AN
/IRQ
3
3
/AN
input pin
3
3
/TMIC input pin
1
4
3
IRQ1
1
0
R/W
is used as PB
/AN
1
3
3
2
1
1
1
pin function. Upon reset,
3
or as IRQ
/TMIC.
1
(initial value)
/TMIC pin.
1
Rev. 6.00, 08/04, page 231 of 628
0
1
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