APPENDIX D LIST OF CAUTIONS
User’s Manual U17446EJ3V1UD
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(15/19)
Chapter
Cl
assi
fi
cati
on
Function Details
of
Function
Cautions Page
Settings and
operating
statuses in HALT
mode
Because an interrupt request signal is used to clear the standby mode, if there
is an interrupt source with the interrupt request flag set and the interrupt mask
flag reset, the standby mode is immediately cleared if set.
p.238
Chapter 1
4
Soft
Standby
function
Settings and
operating
statuses in STOP
mode
Because an interrupt request signal is used to clear the standby mode, if there
is an interrupt source with the interrupt request flag set and the interrupt mask
flag reset, the standby mode is immediately cleared if set. Thus, in the STOP
mode, the normal operation mode is restored after the STOP instruction is
executed and then the operation is stopped for 34
μ
s (TYP.) (after an
additional wait time for stabilizing the oscillation set by the oscillation
stabilization time select register (OSTS) has elapsed when crystal/ceramic
oscillation is used).
p.241
For an external reset, input a low level for 2
μ
s or more to the RESET pin.
p.245
During reset signal generation, the system clock and low-speed internal
oscillation clock stop oscillating.
p.245
When the RESET pin is used as an input-only port pin (P34), the 78K0S/KB1+
is reset if a low level is input to the RESET pin after reset is released by the
POC circuit and before the option byte is referenced again. The reset status is
retained until a high level is input to the RESET pin.
p.245
−
The LVI circuit is not reset by the internal reset signal of the LVI circuit.
p.246
Timing of reset
by overflow of
watchdog timer
The watchdog timer is also reset in the case of an internal reset of the
watchdog timer.
p.248
Chapter 1
5
Hard
Reset
function
RESF: Reset
control flag
register
Do not read data by a 1-bit memory manipulation instruction.
p.252
Soft
If an internal reset signal is generated in the POC circuit, the reset control flag
register (RESF) is cleared to 00H.
p.253
Hard
Functions of
power-on-clear
circuit
Because the detection voltage (V
POC
) of the POC circuit is in a range of 2.1 V
±
0.1 V, use a voltage in the range of 2.2 to 5.5 V.
p.253
Chapter 1
6
Soft
Power-on-
clear circuit
Cautions for
power-on-clear
circuit
In a system where the supply voltage (V
DD
) fluctuates for a certain period in
the vicinity of the POC detection voltage (V
POC
), the system may be
repeatedly reset and released from the reset status. In this case, the time
from release of reset to the start of the operation of the microcontroller can be
arbitrarily set by taking the following action.
p.255
To stop LVI, follow either of the procedures below.
•
When using 8-bit manipulation instruction: Write 00H to LVIM.
•
When using 1-bit memory manipulation instruction: Clear LVION to 0.
p.258
LVIM: Low-
voltage detect
register
Be sure to set bits 2 to 6 to 0.
p.258
Bits 4 to 7 must be set to 0.
p.259
LVIS: Low-
voltage detection
level select
register
If values other than same values are written during LVI operation, the value
becomes undefined at the very moment it is written, and thus be sure to stop
LVI (bit 7 of LVIM register (LVION) = 0) before writing.
p.259
<1> must always be executed. When LVIMK = 0, an interrupt may occur
immediately after the processing in <3>.
p.260
Chapter 1
7
Soft
Low-
voltage
detector
When used as
reset
If supply voltage (V
DD
)
≥
detection voltage (V
LVI
) when LVIM is set to 1, an
internal reset signal is not generated.
p.260