m37905 Renesas Electronics Corporation., m37905 Datasheet - Page 81

• Manufacturer Part Number: m37905
• Description: Mitsubishi 16-bit Single-chip Microcomputer 7700 Family / 7900 Series
• Manufacturer: Renesas Electronics Corporation.

described below.
and properly evaluate their performance.
Notes 1: When leaving these pins open after they have been set to the output mode, note the following:
INPUT/OUTPUT PINS
5.3 Examples of handling unused pins
5.3 Examples of handling unused pins
When unusing an I/O pin, some handling is necessary for this pin. Examples of handling unused pins are
The following are just examples. In actual use, the user shall modify them according to the user’s application
Table 5.3.1 Example of handling unused pins
Fig. 5.3.1 Example of handling unused pins
5-8
P1, P2, P4 to P8
P4OUT
X
AV
AV
OUT
CC
SS
, V
(Note 2), V
2: This applies when a clock externally generated is input to pin X
3: Be sure that the PLL circuit operation enable bit (bit 1 at address BC
CUT
REF
these port pins are placed in the input mode from reset until they are switched to the output mode
by software. Therefore, voltage levels of these pins are undefined and the power source current
may increase while these port pins are placed in the input mode.
Software reliability can be enhanced by setting the contents of the above ports’ direction registers
periodically. This is because these contents may be changed by noise, a program runaway which
occurs owing to noise, etc.
For unused pins, use the shortest possible wiring (within 20 mm from the microcomputer’s pins).
/INT
0,
P6OUT
When setting port pins to input mode
CONT
P4OUT
P6OUT
(Note 3)
Pin name
P1, P2, P4 to P8
CUT
/INT
CUT
CUT
/INT
/INT
V
4
AV
AV
X
V
CONT
0
4
OUT
REF
CC
SS
Left open
V
7905 Group User’s Manual Rev.1.0
CC
V
CC
V
SS
Set these pins to the input mode and connect each
pin to Vcc or Vss via a resistor; or set these pins to
the output mode and leave them open (Note 1).
Connect this pin to Vcc via a resistor.
Select a falling edge for pins INT
Leave these pins open.
Connect this pin to Vcc.
Connect these pins to Vss.
When setting port pins to output mode
P4OUT
P6OUT
P1, P2, P4 to P8
CUT
CUT
Handling example
16
/INT
/INT
) = “0.”
V
AV
AV
IN
V
X
CONT
0
4
OUT
REF
.
CC
SS
Left open
Left open
V
CC
V
CC
0
and INT
V
SS
4
.