ht82k70e-l Holtek Semiconductor Inc., ht82k70e-l Datasheet - Page 26

• Manufacturer Part Number: ht82k70e-l
• Description: I/o Type 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

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
Rev. 1.00
RES Pin Reset
This type of reset occurs when the microcontroller is
already running and the RES pin is forcefully pulled
low by external hardware such as an external switch.
In this case as in the case of other reset, the Program
Counter will reset to zero and program execution initi-
ated from this point. Note that as the external reset pin
is also pin-shared with PA7, if it is to be used as a reset
pin, the correct reset configuration option must be se-
lected.
Watchdog Time-out Reset during Normal Operation
The Watchdog time-out Reset during normal opera-
tion is the same as a hardware RES pin reset except
that the Watchdog time-out flag TO will be set to 1 .
Watchdog Time-out Reset during Power Down
The Watchdog time-out Reset during Power Down is
a little different from other kinds of reset. Most of the
conditions remain unchanged except that the Pro-
gram Counter and the Stack Pointer will be cleared to
Characteristics for t
WDT Time-out Reset during Normal Operation
0 and the TO flag will be set to 1 . Refer to the A.C.
Low Voltage Reset Timing Chart
RES Reset Timing Chart
Timing Chart
SST
details.
26
Power Down function or Watchdog Timer. The reset
flags are shown in the table:
Note: u stands for unchanged
The following table indicates the way in which the vari-
ous components of the microcontroller are affected after
a power-on reset occurs.
TO PDF
Program Counter
Interrupts
WDT
Timer/Event
Counter
Prescaler
Input/Output Ports I/O ports will be setup as inputs
Stack Pointer
0
0
u
1
1
0
1
u
u
1
Item
RES reset during power-on
RES wake-up during Power Down
RES reset during normal operation
WDT time-out reset during normal operation
WDT time-out reset during Power Down
HT82K70E-L/HT82K76E-L
Reset to zero
All interrupts will be disabled
Clear after reset, WDT begins
counting
Timer Counter will be turned off
The Timer Counter Prescaler will
be cleared
Stack Pointer will point to the top
of the stack
RESET Conditions
Condition After RESET
September 15, 2009