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DESCRIPTION
7702/7703 Group User’s Manual
1–10
1.3 Pin description
(2)
In memory expansion mode
Table 1.3.5 Example for processing unused pins in memory expansion mode
Pin name
Ports P42 to P47, P5 to P8
____
BHE (Note 2)
ALE (Note 3)
_____
HLDA (Note 6)
XOUT (Note 5)
_____
____
HOLD, RDY (Note 8)
AVcc
AVss, VREF
Example of processing
Set for input mode and connect these pins to Vcc or
Vss via a resistor; or set for output mode and leave
these pins open. (Notes 1, 6, 7)
Leave them open. (Note 4)
Leave it open.
Connect these pins to Vcc via a resistor (pull-up).
Connect this pin to Vcc.
Connect these pins to Vss.
Notes 1: When setting these ports to the output mode and leave them open, they remain set to the input
mode until they are switched to the output mode by software after reset. While ports remain set
to the input mode, consequently, voltage levels of pins are unstable, and a power source current can increase.
The contents of the direction register can be changed by noise or a program runaway generated
by noise. To improve its reliability, we recommend to periodically set the contents of the direction
register by software.
When processing unused pins, use the possible shortest wiring (within 20 mm from the microcomputer).
2: This applies when “H” level is input to the BYTE pin.
3: This applies when “H” level is input to the BYTE pin and the access space is 64 Kbytes.
4: When supplying Vss level to the CNVss pin, these pins remain set to the input mode until they
are switched to the output mode by software after reset. While pins remain set to the input mode,
consequently, voltage levels of pins are unstable, and a power source current can increase.
5: This applies when a clock externally generated is input to the XIN pin.
6: In the 7703 Group, the following ports does not have the corresponding pins and have only the
direction registers. Fix the bit of these direction registers to “1” (output mode).
Ports P43–P46, P60, P61, P66, P67, P73–P76, P84, P85
_____
There is not the HLDA pin.
7: Set the P42/
φ1 pin to the P42 function (clock φ1 output disabled), and perform the same processing
as ports P43–P47, P5–P8.
8: When processing unused pins, use the possible shortest wiring (within 20 mm from the microcomputer).
P42–P47, P5–P8
AVSS
VREF
HOLD
RDY
M37702
VCC
VSS
AVCC
XOUT
BHE
ALE
HLDA
P42–P47, P5–P8
AVSS
VREF
HOLD
RDY
VSS
AVCC
XOUT
BHE
ALE
HLDA
VCC
M37702
Left open
q When setting ports for input mode
q When setting ports for output mode
Left open
Fig. 1.3.2 Example for processing unused pins in memory expansion mode