4513_03 Datasheet, PDF (113/210 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.1 I/O pins
Table 2.1.6 connections of unused pins
Pin
Connection
XOUT
Open (when using an external clock).
VDCE
Connect to VSS.
D0–D5
Connect to VSS, or set the output latch to “0” and open.
D6/CNTR0
D7/CNTR1
P20/SCK
Connect to VSS.
P21/SOUT
P22/SIN
P30/INT0
Connect to VSS, or set the output latch to “0” and open.
P31/INT1
P32, P33
P40/AIN4–P43/AIN7
Connect to VSS, or set the output latch to “0” and open.
P50–P53 (Note 1)
When the input mode is selected by software, pull-up to VDD through a resistor or
pull-down to VSS. When selecting the output mode, open.
AIN0/CMP0-
Connect to VSS.
AIN1/CMP0+
AIN2/CMP1-
AIN3/CMP1+
P00–P03
Open or connect to VSS (Note 2).
P10–P13
Open or connect to VSS (Note 2).
Notes 1: After system is released from reset, port P5 is in an input mode (direction register FR0 = 00002)
2: When the P00–P03 and P10–P13 are connected to VSS, turn off their pull-up transistors (register
PU0i=“0”) and also invalidate the key-on wakeup functions (register K0i=“0”) by software. When
these pins are connected to VSS while the key-on wakeup functions are left valid, the system fails
to return from RAM back-up state. When these pins are open, turn on their pull-up transistors
(register PU0i=“1”) by software, or set the output latch to “0.”
Be sure to select the key-on wakeup functions and the pull-up functions with every two pins. If
only one of the two pins for the key-on wakeup function is used, turn on their pull-up transistors
by software and also disconnect the other pin. (i = 0, 1, 2, or 3.)
(Note in order to set the output latch to “0” and make pins open)
• After system is released from reset, a port is in a high-impedance state until the output latch of the port
is set to “0” by software. Accordingly, the voltage level of pins is undefined and the excess of the supply
current may occur.
• To set the output latch periodically is recommended because the value of output latch may change by
noise or a program run away (caused by noise).
(Note in order to connect unused pins to VSS or VDD)
• To avoid noise, connect the unused pins to VSS or VDD at the shortest distance using a thick wire.
2-10
4513/4514 Group User’s Manual