M16C26A Datasheet, PDF (246/352 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/Tiny SERIES

M16C/26A Group (M16C/26A, M16C/26B, M16C/26T)
16. Programmable I/O Ports
Table 16.1. Unassigned Pin Handling in Single-chip Mode
Pin name
Connection
Ports P1, P6 to P10
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. ^{(1, 2, 4)}
XOUT ⁽³⁾
XIN
AVCC
AVSS, VREF
Open
Connect via resistor to V CC (pull-up) ⁽⁵⁾
Connect to V CC
Connect to V SS
NOTES:
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 direction registers be periodically reset in software,
for the increased reliability of the program.
2. Make sure the unused pins are processed with the shortest possible wiring from the microcomputer pins (within 2
cm).
3. With external clock or VCC input to XIN pin.
4. When using the 48-pin package, set PACR2, PACR1, PACR0 to "1002".When using the 42-pin package, set
PACR2, PACR1, PACR0 to "0012".
5. When the main clock oscillation circuit is not used, set the CM05 bit in the CM0 register to “0” (main clock stops)
to reduce power consumption.
Microcomputer
Port P1, P6 to P10
(1)
(Input mode)
···
(Input mode)
(Output mode)
XIN
XOUT
AVCC
···
Open
Open
VCC
AVSS
VREF
VSS
In single-chip mode
NOTE:
1. When using the 48-pin package, set PACR2, PACR1, PACR0 to "1002".
When using the 42pin-package, set PACR2, PACR1, PACR0 to "0012".
Figure 16.7. Unassigned Pins Handling
Rev. 2.00 Feb.15, 2007 ^{page 229} of 329
REJ09B0202-0200