4513_03 Datasheet, PDF (188/210 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCOMPUTER

APPENDIX
3.3 List of precautions
3.3 List of precautions
ŒNoise 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 relatively thick wire.
In the One Time 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 kΩ in series at the shortest distance.
 Prescaler
Stop the prescaler operation to change its frequency dividing ra-
tio.
ŽTimer count source
Stop timer 1, 2, 3, or 4 counting to change its count source.
Reading the count value
Stop timer 1, 2, 3, or 4 counting and then execute the TAB1,
TAB2, TAB3, or TAB4 instruction to read its data.
Writing to reload registers R1 and R3
When writing data to reload registers R1 or R3 while timer 1 or
timer 3 is operating, avoid a timing when timer 1 or timer 3
underflows.
‘P30/INT0 pin
When the interrupt valid waveform of the P30/INT0 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” before the interrupt valid wave-
form of P30/INT0 pin is changed with the bit 2 of register I1 (refer
to Figure 44Œ).
• Depending on the input state of the P30/INT0 pin, the external 0
interrupt request flag (EXF0) may be set when the interrupt valid
waveform is changed. Accordingly, clear bit 2 of register I1, and
execute the SNZ0 instruction to clear the EXF0 flag after execut-
ing at least one instruction (refer to Figure 44)
’P31/INT1 pin
When the interrupt valid waveform of P31/INT1 pin is changed
with the bit 2 of register I2 in software, be careful about the fol-
lowing notes.
• Clear the bit 1 of register V1 to “0” before the interrupt valid wave-
form of P31/INT1 pin is changed with the bit 2 of register I2 (refer
to Figure 45Ž).
• Depending on the input state of the P31/INT1 pin, the external 1
interrupt request flag (EXF1) may be set when the interrupt valid
waveform is changed. Accordingly, clear bit 2 of register I2 and
execute the SNZ1 instruction to clear the EXF1 flag after execut-
ing at least one instruction (refer to Figure 45).
._..
LA 8
TV1A
LA 8
TI2A
NOP
SNZ1
NOP
._..
; (!!0!2)
; The SNZ1 instruction is valid ........... Ž
; Change of the interrupt valid waveform
........................................................... 
; The SNZ1 instruction is executed
! : this bit is not related to the setting of INT1.
Fig. 45 External 1 interrupt program example
“One Time PROM version
The operating power voltage of the One Time PROM version is
2.5 V to 5.5 V.
” Multifunction
The input of D6, D7, P20–P22, I/O of P30 and P31, input of CMP0-,
CMP0+, CMP1-, CMP1+, and I/O of P40–P43 can be used even
when CNTR0, CNTR1, SCK, SOUT, SIN, INT0, INT1, AIN0–AIN3
and AIN4–AIN7 are selected.
._..
LA 4
TV1A
LA 4
TI1A
NOP
SNZ0
NOP_...
; (!!!02)
; The SNZ0 instruction is valid ........... Œ
;
; Interrupt valid waveform is changed
........................................................... 
; The SNZ0 instruction is executed
! : this bit is not related to the setting of INT0 pin.
Fig. 44 External 0 interrupt program example
4513/4514 Group User’s Manual
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