M37632EFFP#U2 Renesas Electronics America, M37632EFFP#U2 Datasheet - Page 113

• Manufacturer Part Number: M37632EFFP#U2
• Description: IC 740 MCU 80QFP
• Manufacturer: Renesas Electronics America

Specifications of M37632EFFP#U2

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4. NOTES ON USE
The information below applies to the entire 740 Family. Please refer to it in conjunction with
the usage notes of each specific product model.
4.1 Notes on input and output ports
Rev.2.00 Nov 14, 2006
REJ09B0322-0200
4.1.1 Notes in standby state
In standby state
In addition, the same note is necessary even when N-channel open-drain I/O ports are set
to output mode.
Pull-up (connect the port to V
a resistor.
When determining a resistance value, note the following points:
• External circuit
• Variation of output levels during the ordinary operation
4.1.2 Modifying output data with bit managing instruction
When the port latch of an I/O port is modified with the bit managing instruction
of the unspecified bit may be changed.
Reason
Reason
An transistor becomes an OFF state when an I/O port is set as input mode by the direction
register, so that the port enter a high-impedance state. At this time, the potential which
is input to the input buffer in a microcomputer is unstable in the state that input levels are
“undefined”. This may cause power source current. Even when an I/O port of N-channel
open-drain is set as output mode by the direction register, if the contents of the port latch
is “1”, the same phenomenon as that of an input port will occur.
I/O ports are set to input or output mode in bit units. Reading from a port register or writing
to it involves the following operations.
• Port in input mode
• Port in output mode
Since bit managing instructions
on a port register causes a read and write to be performed simultaneously on the bits
other than the one specified by the instruction.
When an unspecified bit is in input mode, its pin level is read and that value is written to
the port latch. If the previous value of the port latch differs from the pin level, the port latch
value is changed.
If an unspecified bit is in output mode, the port latch is generally read. However, for some
ports the peripheral function output is read, and the value is written to the port latch. In
this case, if the previous value of the port latch differs from the peripheral function output,
the port latch value is changed.
1 standby state: Stop mode by executing STP instruction
1. Bit managing instructions: SEB and CLB instructions
2. Read-modify-write instructions: Instructions that read memory in byte units, modify the
Read: Read the pin level.
Write: Write to the port latch.
Read: Read the port latch or read the output from the peripheral function (specifications
differ depending on the port).
Write: Write to the port latch. (The port latch value is output from the pin.)
value, and then write the result to the same location in memory in byte units
1
, do not make pin levels “undefined” when I/O ports are set to input mode.
Wait mode by executing WIT instruction
page 105 of 185
CC
) or pull-down (connect the port to V
1
are read-modify-write instructions,
NOTES ON USE
2
using such an instruction
SS
) these ports through
2
, the value