Renesas 4514 - Manual (Page 188)

4513/4514 Group User’s Manual
APPENDIX
3-21
3.3 List of precautions
3.3 List of precautions
➀ Noise and latch-up prevention
Connect a capacitor on the following condition to prevent noise
and latch-up;
• connect a bypass capacitor (approx. 0.1
µ
F) between pins V DD
and V SS at the shortest distance,
• equalize its wiring in width and length, and
• use relatively thick wire.
In the One Time PROM version, CNV SS pin is also used as V PP
pin. Accordingly, when using this pin, connect this pin to V SS
through a resistor about 5 k
Ω
in series at the shortest distance.
➁ Prescaler
Stop the prescaler operation to change its frequency dividing ra-
tio.
➂ Timer count source
Stop timer 1, 2, 3, or 4 counting to change its count source.
➃ 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.
➄ 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.
➅ P3 0 /INT0 pin
When the interrupt valid waveform of the P3 0 /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 P3 0 /INT0 pin is changed with the bit 2 of register I1 (refer
to Figure 44 ➀ ).
• Depending on the input state of the P3 0 /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 ➁ )
Fig. 45 External 1 interrupt program example
➇ One Time PROM version
The operating power voltage of the One Time PROM version is
2.5 V to 5.5 V.
➈ Multifunction
The input of D 6 , D 7 , P2 0 –P2 2 , I/O of P3 0 and P3 1 , input of CMP0-,
CMP0+, CMP1-, CMP1+, and I/O of P4 0 –P4 3 can be used even
when CNTR0, CNTR1, S CK , S OUT , S IN , INT0, INT1, A IN0 –A IN3
and A IN4 –A IN7 are selected.
➆ P3 1 /INT1 pin
When the interrupt valid waveform of P3 1 /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 P3 1 /INT1 pin is changed with the bit 2 of register I2 (refer
to Figure 45 ➂ ).
• Depending on the input state of the P3 1 /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 ➃ ).
LA 8 ; ( ✕✕ 0 ✕ 2 )
TV1A ; The SNZ1 instruction is valid ........... ➂
LA 8
TI2A ; Change of the interrupt valid waveform
NOP ........................................................... ➃
SNZ1 ; The SNZ1 instruction is executed
NOP
✕ : this bit is not related to the setting of INT1.
...
...
LA 4 ; ( ✕✕✕ 0 2 )
TV1A ; The SNZ0 instruction is valid ........... ➀
LA 4 ;
TI1A ; Interrupt valid waveform is changed
NOP ........................................................... ➁
SNZ0 ; The SNZ0 instruction is executed
NOP
✕ : this bit is not related to the setting of INT0 pin.
...
...
Fig. 44 External 0 interrupt program example