UPD78044F datasheet(90/472 Pages) NEC

90 / 472 page

Chapter 4

Port Functions

User’s Manual U16504EE1V1UD00

4.2.4 Port 3

Port 3 is an 4-bit input/output port with output latch. P34 to P37 pins can specify the input mode/output

mode in 1-bit units with the port mode register 3 (PM3). When P34 to P37 are used as input pins,

pull-up resistors can be connected bit-wise with the pull-up resistor option register (PU3).

Dual-function includes timer input/output, serial interface data input/output, serial interface clock

input/output and segment signal output of the LCD controller/driver.

RESET input sets port 3 to input mode.

Figure 4-5 shows a block diagram of port 3.

Caution:

When used as segment lines, set the port function (PF3) according to its function.

Figure 4-5:

P34 to P37 Configurations

Remarks: 1. PM

: Port mode register

2. RD

: Port 3 read signal

3. WR

: Port 3 write signal

Notes: 1. Set output latch to 0 when dual function shall be applied to output.

2. Disable dual function when the comment of the output latch shall be applied to output.

WRPM

WRPORT

Selector

Output Latch

(P34 to P37)

PM34 to PM37

Dual Function

P34/TO50/TI50/S27

P35/SCK3/S26

P36/SO3/S25

P37/SI3/S24

Note 1

Note 2

UPD78044F Datasheet(PDF) 90 Page - NEC