RL78/G1P
CHAPTER 19 VOLTAGE DETECTOR
R01UH0895EJ0100 Rev.1.00
641
Nov 29, 2019
19.5 Cautions for Voltage Detector
(1) Voltage fluctuation when power is supplied
In a system where the supply voltage (V
DD
) fluctuates for a certain period in the vicinity of the LVD detection voltage,
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.
<Action>
After releasing the reset signal, wait for the supply voltage fluctuation period of each system by means of a software
counter that uses a timer, and then initialize the ports.
Figure 19-9. Example of Software Processing If Supply Voltage Fluctuation is 50
s or Less in Vicinity of LVD
Detection Voltage
Reset
Yes
No
Clearing WDT
Refer to
Figure 17-5 Procedure for Checking Reset Source.
;
Note
Timer starts (TSmn = 1).
Source: f
MCK
= (4.04 MHz (MAX.))/2
8
,
where comparison value = 789:
≈
50 ms
; e.g. f
CLK
= High-speed on-chip oscillator clock (4.04 MHz (MAX.))
Initial setting for port.
Setting of division ratio of system clock,
such as setting of timer or A/D converter.
Initialization processing <1>
Setting timer array unit
(to measure 50 ms)
50 ms have passed?
(TMIFmn = 1?)
Initialization processing <2>
Note
If reset is generated again during this period, initialization processing <2> is not started.
Remark
m = 0
n = 0 to 3