
HD404889/HD404899/HD404878/HD404868 Series
67
Input/Output
The MCU has 46 input/output pins (D
0
to D
11
, R0 to R7, R8
0
, and R8
1
) in the HD404889, HD404899, and
HD404878 Series, or 41 input/output pins (D
0
to D
9
, R0
0
, R0
1
, R0
2
, and R1 to R7) in the HD404868 Series.
The features of these pins are described below.
The four pins D
0
to D
3
are source large-current (10 mA max.) I/O pins.
The eight pins D
4
to D
11
are sink large-current (15 mA max.) I/O pins.
I/O pins comprise pins (D
0
, D
1
, R
0
, R
1
, R2
0
to R2
2
, R3 to R7, R8
0
, and R8
1
) that also have a peripheral
function (timer, serial interface, etc.). With these pins, the peripheral function setting has priority over
the D port or R port pin setting. When a peripheral function setting has been made for a pin, the pin
function and input/output mode will be switched automatically in accordance with that setting.
Selection of input or output for I/O pins, or selection of the port or peripheral function for pins
multiplexed as peripheral function pins, is performed by the program.
All output of the peripheral function pins are CMOS outputs. The SO pin and R2
2
port pin can be
designated as NMOS open-drain output by the program.
A reset clears peripheral function selection. And since the data control registers (DCD, DCR) are also
reset, input/output pins go to the high-impedance state.
Each I/O pin has a built-in pull-up MOS that can be turned on and off individually by the program.
Figure 26 shows the I/O buffer configuration, and table 22 shows I/O pin circuit configuration control by
the program.
Table 23 shows the circuit configuration of each I/O pin.
pull-up
MOS
Pull-up control signal
Buffer control signal
Output data
Input data
V
CC
PMOS
NMOS
Input control signal
MIS3
DCD, DCR
PDR
V
CC
Figure 26 I/O Pin Circuit Configuration