Rev. 1.50
60
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Rev. 1.50
61
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HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
Watchdog Time-out Reset during Normal Operation
The Watchdog time-out Reset during normal operation is the same as the hardware Low Voltage
Reset except that the Watchdog time-out flag TO will be set to “1”.
WDT Time-o�t
Internal Reset
t
RSTD
+ t
SST
Note: t
RSTD
is power-on delay with typical time = 16.7 ms
WDT Time-out Reset during NORMAL Operation Timing Chart
Watchdog Time-out Reset during SLEEP or IDLE Mode
The Watchdog time-out Reset during SLEEP or IDLE Mode is a little different from other kinds
of reset. Most of the conditions remain unchanged except that the Program Counter and the Stack
Pointer will be cleared to “0” and the TO flag will be set to “1”. Refer to the A.C. Characteristics for
t
SST
details.
WDT Time-o�t
Internal Reset
t
SST
WDT Time-out Reset during SLEEP or IDLE Mode Timing Chart
Reset Initial Conditions
The different types of reset described affect the reset flags in different ways. These flags, known
as PDF and TO are located in the status register and are controlled by various microcontroller
operations, such as the SLEEP or IDLE Mode function or Watchdog Timer. The reset flags are
shown in the table:
TO
Reset Function
0
0
Power-on reset
�
�
LVR reset d�rin� NORM�L or SLOW Mode operation
1
�
WDT time-o�t reset d�rin� NORM�L or SLOW Mode operation
1
1
WDT time-o�t reset d�rin� IDLE or SLEEP Mode operation
“�” stands for �nchan�ed
The following table indicates the way in which the various components of the microcontroller are
affected after a power-on reset occurs.
Item
Reset Function
Pro�ram Co�nter
Reset to zero
Interr�pts
�ll interr�pts will be disabled
WDT� Time Base
Clear after reset� WDT be�ins co�ntin�
Timer Mod�les
Timer Mod�les will be t�rned off
Inp�t/O�tp�t Ports
I/O ports will be set�p as inp�ts
Stack pointer
Stack pointer will point to the top of the stack
The different kinds of resets all affect the internal registers of the microcontroller in different ways.
To ensure reliable continuation of normal program execution after a reset occurs, it is important to
know what condition the microcontroller is in after a particular reset occurs. The following table
describes how each type of reset affects the microcontroller internal registers. Note that where more
than one package type exists the table will reflect the situation for the larger package type.