UPD78C18 datasheet(24/110 Pages) NEC

24 / 110 page

µPD78C17,78C18

(2)

PB7 to PB0 (PORT B)

Like port A, port B is an 8-bit input/output port with input/output buffer and output latch functions. Port B

can be set as an input or output port bit-wise using the MODE B register (MB).

µPD78C18 port B pull-up

resistor specification is performed bit-wise by mask option.

Port B is set as follows when setting the input port or after reset.

High-impedance : Without pull-up resistor

High level

: With pull-up resistor

As with port A, direct bit setting/resetting of port B output latch contents is possible by an arithmetic or

logical operation instruction without the use of an accumulator. Data transfer to/from an accumulator is

also possible.

•

MODE B Register (MB)

Like the MODE A register, the MODE B register is an 8-bit register which specifies port B input/

output bit-wise.

After RESET input or in the hardware STOP mode, all the bits are set (1), and port B is in the input

mode resulting in the status below.

High-impedance : Without pull-up resistor

High level

: With pull-up resistor

Fig. 2-9 Mode B Register Format

MB 7

MB 6

MB 5

MB 4

MB 3

MB 2

MB 1

(n = 0 to 7)

PBn = Output

PBn = Input

MB 0

76543210

UPD78C18 Datasheet(PDF) 24 Page - NEC