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M34551E4-XXXFP View Datasheet(PDF) - Renesas Electronics

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M34551E4-XXXFP Datasheet PDF : 69 Pages
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MITSUBISHI MICROCOMPUTERS
4551 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for
INFRARED REMOTE CONTROL TRANSMITTER
LIST OF PRECAUTIONS
ΠNoise and latch-up prevention
Connect a capacitor on the following condition to prevent noise
and latch-up;
• connect a bypass capacitor (approx. 0.1 µF) between pins
VDD and VSS at the shortest distance,
• equalize its wiring in width and length, and
• use the thickest wire.
In the built-in PROM version, CNVSS pin is also used as VPP
pin. Accordingly, when using this pin, connect this pin to VSS
through a resistor about 5 k(connect this resistor to CNVSS/
VPP pin as close as possible).
 Prescaler
Stop the prescaler operation to change its frequency dividing
ratio.
Ž Count source
Stop timer 1 or timer LC counting to change its count source.
When timer 2 count source changes from f(XCIN) to ORCLK
(W23 = “0” W23 = “1”), the count value of timer 2 is initialized.
However, when timer 2 count source changes from ORCLK to
f(XCIN) (W23 = “1” W23 = “0”) or the same count source is
set again (W23 = “0” W23 = “0” or W23 = “1” W23 = “1”),
the count value of timer 2 is not initialized.
 Timer 2
Timer 2 has the watchdog timer function (WDT). When timer 2
is used as the WDT, note that the processing to initialize the
count value and the execution of the WRST instruction.
 Reading the count value
Stop the prescaler and then execute the TAB1 instruction to
read timer 1 data.
‘ Writing to reload register R1
Write the data to reload register R1 while timer 1 is operating,
avoid a timing when timer 1 underflows.
’ Notes when using the carrier wave output auto-control function
• Execute the STCR instruction after setting the timer 1 and
register C2 in order to start the carrier generating circuit
operation.
• Stop the timer 1 (W20=“0”) after stopping the carrier
generating circuit (SPCR instruction executed) while the
carrier wave output is disabled in order to stop the carrier
wave output auto-control operation.
• If the carrier wave output auto-control function is invalidated
(C20=“0”) while the carrier wave output is auto-controlled,
the output of port CARR retains the state when the auto-
control is invalidated regardless of timer 1 underflow. This
state is released by timer 1 stop (W20=“0”).
When the carrier wave output auto-control function is
validated (C20=“1”) again after it is invalidated (C20=“0”),
the auto-control of carrier wave output is started again when
the next timer 1 underflow occurs. However, when the carrier
wave output auto-control bit is changed during timer 1
underflow, the error-operation may occur.
• Use the carrier wave or the carrier wave divided by 2 as the
timer 1 count source when the carrier wave output auto-
control function is selected.
If the ORCLK is used as the count source, a hazard may
occur in port CARR output because ORCLK is not
synchronized with the carrier wave.
“ D5/INT pin
When the interrupt valid waveform of D5/INT pin is changed
with the bit 2 of register I1 in software, be careful about the
following notes.
• Clear the bit 0 of register V1 to “0” and then change the
interrupt valid waveform of D5/INT pin with the bit 2 of register
I1 (refer to Figure 40Œ).
• Clear the bit 2 of register I1 to “0” and execute the SNZ0
instruction to clear the EXF0 flag after executing at least
one instruction (refer to Figure 40). Depending on the input
state of the D5/INT pin, the external 0 interrupt request flag
(EXF0) may be set to “1” when the interrupt valid waveform
is changed.
...
LA
TV1A
LA
TI1A
NOP
SNZ0
NOP
...
4 ; (!!!02)
; The SNZ0 instruction is valid Œ
4
; Change of the interrupt valid waveform

;The SNZ0 instruction is executed
! : this bit is not related to the setting of INT.
Fig. 40 External 0 interrupt program example
” One Time PROM version
The operating power voltage of the One Time PROM version
is within the range of 2.5 V to 5.5 V.
• Multifunction
Note that the port D5 output function can be used even when
INT function is selected.
11Power down instruction (POF instruction, POF2 instruction)
Execute the POF or POF2 instruction immediately after
executing the EPOF instruction to enter the power down state.
Note that system cannot enter the power down state when
executing only the POF or POF2 instruction.
12Program counter
Make sure that the PCH does not specify after the last page of
the built-in ROM.
38
 

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