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M16C/29 Group
Table 19.1. Unassigned Pin Handling in Single-chip Mode
Pin name
Ports P0 to P3,
P6 to P10
X
(Note 3)
OUT
Xin
AV
CC
AV
, V
SS
REF
Note 1: When setting the port for output mode and leave it open, be aware that the port remains in input
mode until 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.
Futhermore, 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
directionregisters be periodically reset in software, for the increased reliability of the program.
Note 2: Make sure the unused pins are processed with the shortest possible wiring from the microcomputer
pins (within 2 cm).
Note 3: With external clock or V
Note 4: When using the 80pin version, set PACR2, PACR1, PACR0 to "011
When using the 64pin version, set PACR2, PACR1, PACR0 to "010
Figure 19.7. Unassigned Pins Handling
Rev.1.00 Nov 01,2004
REJ09B0101-0100Z
After setting for input mode, connect every pin to V
or after setting for output mode, leave these pins open. (Note 1, Note 2, Note 4)
Open
Connect via resistor to V
Connect to V
CC
Connect to V
SS
input to X
CC
Microcomputer
Port P0 to P3, P6 to P10
(Note)
(Input mode)
·
·
·
(Input mode)
(Output mode)
X
X
OUT
AV
AV
V
REF
In single-chip mode
Note : when using the 64pin version, set PACR2, PACR1, PACR0 to "010
page 322 of 402
Connection
(pull-up)
CC
pin.
IN
·
·
·
Open
IN
Open
V
CC
CC
SS
V
SS
19. Programmable I/O Ports
via a resistor(pull-down);
SS
".
2
".
2
".
2
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