
261
Table 11-1 Port Functions (cont)
Port
Overview
Pin
Shared Function
Function
Switching
Register
R1, R2,
R8, R9
High voltage I/O ports
Accessed in 4-bit units.
Accessed with the LAR, LBR,
LRA, and LRB instructions.
Pull-down resistors available
as a mask option.
R1
0 to R13
R2
0 to R23
R8
0 to R83
R9
0 to R93
——
RA
High voltage input port (1 bit)
Accessed with the LAR and
LBR instructions.
RA
1/V disp
High voltage
pin output power supply
Mask
option
11.1.2
I/O Control
The D, R1, R2, R8, and R9 ports are high voltage I/O ports, RA
1 is a 1-bit high voltage input port,
and R0 and R3 to R7 are standard voltage I/O ports. The different port types have different circuit
structures as follows.
(1) High Voltage I/O Pin Circuit: The D, R1, R2, R8, and R9 port pins are high voltage I/O pins
that have no I/O switching function. When a port data register is set to 1, the PMOS transistor
turns on and a high level voltage is output from the pin. When the PDR is set to 0, the pin goes to
the open state. If the built-in pull-down resistor mask option was selected, the V
disp voltage is
output. When external signals are applied, applications must set the PDR value to 0 so that the
external (input) and internal (output) signals do not collide at the pin.
Note that there are no pull-down resistors on the high voltage I/O pins in the ZTAT versions of
these microcomputers.
(2) Standard Voltage CMOS Three State I/O Pin Circuit: The pins in the R0 and R3 to R7
ports are standard voltage CMOS three state I/O ports. I/O through these ports is controlled by the
PDRs and the data control registers (DCR). When the DCR bit corresponding to a given pin is 1,
that pin functions as an output pin and outputs the value in the PDR. When a given DCR bit is 0,
the corresponding pin functions as an input pin.