Datasheet

M16C/6S Group Programmable I/O Ports
R01DS0201EJ0502 Rev.5.02 page 147 of 203
Dec 25, 2012
Pin name Connection
Ports P1, P6 to P9
(excluding P8
5 )
X
OUT (Note 1)
V
SS A
V CC A
After setting for input mode, connect every pin to V
SS via a resistor(pull-down);
or after setting for output mode, leave these pins open. (2, 3, 4)
Open
Connect to V
CC
Connect to V SS
P8 5
Connect via resistor to V CC (pull-up)
NOTES:
2. When setting the port for output mode and leave it open, be aware that the port remains in input mode until
1. With external clock input to X
IN pin.
it is switched to output mode in a program after reset. For this reason, the voltage level on the pin becomes
indeterminate, causing the power supply current to increase while the port remains in input mode.
Furthermore, by considering a possibility that the contents of the direction registers could be changed by
noise or noise-induced runaway, it is recommended that the contents of the direction registers be
periodically reset in software, for the increased reliability of the program.
3. Make sure the unused pins are processed with the shortest possible wiring from the microcomputer pins
(within 2 cm).
4. When the port P7_0 is set for output mode, make sure a low-level signal is output from the pin.
The port P7_0 is N-channel open-drain output.
Table 1.18.1. Unassigned Pin Handling in Single-chip Mode (Excluding Analog Pins)