
16. Programmable I/O Ports
page 224
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Pin name
Connection
Ports P1, P6 to P10
XOUT (Note 3)
AVSS, VREF
AVCC
After setting for input mode, connect every pin to VSS via a resistor(pull-down);
or after setting for output mode, leave these pins open. (Note 1, Note 2, Note 4)
Open
Connect to VCC
Connect to VSS
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 VCC input to XIN pin.
Note 4: When using the 48pin version, set PACR2, PACR1, PACR0 to "1002".
When using the 42pin version, set PACR2, PACR1, PACR0 to "0012".
Note 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.
Connect via resistor to VCC (pull-up) (Note 5)
Xin
Table 16.1. Unassigned Pin Handling in Single-chip Mode
Figure 16.7. Unassigned Pins Handling
(Input mode)
(Input mode)
(Output mode)
XOUT
AVCC
AVSS
VREF
Microcomputer
VCC
VSS
In single-chip mode
Open
Note : when using the 48pin version, set PACR2, PACR1, PACR0 to "1002".
when using the 42pin version, set PACR2, PACR1, PACR0 to "0012".
(Note)
Port P1, P6 to P10
XIN