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參數(shù)資料
| 型號： | M38C24M4A-XXXFP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | 8-BIT, MROM, 5 MHz, MICROCONTROLLER, PQFP64 |
| 封裝： | 14 X 14 MM, 0.80 MM PITCH, PLASTIC, LQFP-64 |
| 文件頁數(shù)： | 97/102頁 |
| 文件大?。?/td> | 1369K |
| 代理商： | M38C24M4A-XXXFP |
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Rev.2.00
May 28, 2004
page 94 of 100
38C2 Group (A Version)
NOTES ON PERIPHERAL FUNCTIONS
Notes on I/O Ports
1. Pull-up control register
When using each port which built in pull-up resistor as an output
port, the pull-up control bit of corresponding port becomes invalid,
and pull-up resistor is not connected.
<Reason>
Pull-up control is effective only when each direction register is set to
the input mode.
2. Modifying output data with bit managing instruction
When the port latch of an I/O port is modified with the bit managing
instruction (Note), the value of the unspecified bit may be changed.
<Reason>
I/O ports can be set to input or output mode in a bit unit. When read-
ing or writing are performed to the port Pi (i = 0–7) register, the micro-
computer operates as follows.
Port in input mode
-Read-access: reads pin’s level (The contents of port latch and
pin’s level are unrelated.)
-Write-access: writes data to port latch (The contents of port latch
and pin’s level are unrelated.)
Port in output mode
-Read-access: reads port latch (The contents of port latch and pin’s
level are unrelated.)
-Write-access: writes data to port latch (The contents of port latch
are output from the pin.)
The bit managing instructions are read-modify-write form instructions
for reading and writing data by a byte unit.
Therefore, when the bit managing instructions are executed to the
port set to input mode, the instruction read the pin’s states, modify
the specification bit, and then write data to the port latch. At this time,
if the contents of the original port latch are different from the pins’s
level, the contents of the port latch of bit which is not specified by
instruction will change.
In addition to this, if the bit managing instructions are executed to the
port Pi register in order to setting output data when port Pi is config-
ured as a mixed input and output port, the contents of the port latch
of bit in the input mode which is not specified by instruction may
change.
Note: Bit managing instructions: SEB instruction, CLB instruction
3. Port direction register
The port direction registers are write-only registers. Therefore, the
following instructions cannot be used to this register:
LDA instruction
Memory operation instruction when T flag is “1”
Instructions operating in addressing mode that modifies direction
register
Bit test instructions such as BBC and BBS
Bit modification instructions such as CLB and SEB
Arithmetic instructions using read-modify-write form instructions such
as ROR
The LDM, STA instructions etc. are used for setting of the direction
register.
Notes on Termination of Unused Pins
1. Terminate unused pins
Perform the following wiring at the shortest possible distance (20
mm or less) from microcomputer pins.
(1) I/O ports
Set the I/O ports for the input mode and connect each pin to VCC or
VSS through each resistor of 1 k
to 10 k. The port which can se-
lect a built-in pull-up resistor can also use the built-in pull-up resistor.
When using the I/O ports as the output mode, open them at “L” or
“H”.
When opening them in the output mode, the input mode of the initial
status remains until the mode of the ports is switched over to the
output mode by the program after reset. Thus, the potential at these
pins is undefined and the power source current may increase in the
input mode. With regard to an effects on the system, thoroughly
perform system evaluation on the user side.
Since the direction register setup may be changed because of a
program runaway or noise, set direction registers by program peri-
odically to increase the reliability of program.
2. Termination remarks
(1) Input ports
Do not open them.
<Reason>
If the input level is undefined, the power source current may in-
crease.
An effect due to noise may be easily produced as compared with “1.
(1) I/O ports“ shown on the above.
(2) I/O ports setting as input mode
[1] Do not open in the input mode.
<Reason>
The power source current may increase depending on the first-
stage circuit.
An effect due to noise may be easily produced as compared with “1.
(1) I/O ports“ shown on the above.
[2] I/O ports :
Do not connect to VCC or VSS directly.
<Reason>
If the direction register setup changes for the output mode because
of a program runaway or noise, a short circuit may occur.
[3] I/O ports :
Do not connect multiple ports in a lump to VCC or VSS through a
resistor.
<Reason>
If the direction register setup changes for the output mode because
of a program runaway or noise, a short circuit may occur between
ports.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| M38C24M4-XXXFP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| M38C24M4-XXXHP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| M38C24M6-051HP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| M38C24M6-XXXFP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
| M38C24M6-XXXHP | 制造商:MITSUBISHI 制造商全稱:Mitsubishi Electric Semiconductor 功能描述:SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER |
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