Specifications

mikroElektronika | Free Online Book | PIC Microcontrollers | Chapter 3: I/O Ports
Fig. 3-6 WPUB register
Having a high level of resistance (several tens of kilo ohms), these “virtual” resistors do not affect pins configured as
outputs, but serves as a useful complement to inputs. As such, they are connected to CMOS logic circuit inputs.
Otherwise, they would act as if they are floating because of their high input resistance.
Fig. 3-7 Pull-up resistors
* Apart from the bits of the WPUB register, there is another bit affecting pull-up resistors installation. It is RBPU bit of
the OPTION_REG. It is a general-purpose bit because it affects installation of all Port resistors.
If enabled, each Port B bit configured as an input may cause an interrupt by changeing its logic state. In order to
enable pins to cause an interrupt, the appropriate bit of the IOCB register should be set.
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