HT56R66 Holtek Semiconductor Inc., HT56R66 Datasheet - Page 75

• Manufacturer Part Number: HT56R66
• Description: Tinypower Tm A/d Type With Lcd 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

Rev. 1.10
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.
WDT Time-out Reset during Power Down
Timing Chart
Timing Chart
SST
details.
75
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
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.
Program Counter
Interrupts
WDT
Timer/Event Counter Timer Counter will be turned off
Prescaler
Input/Output Ports
Stack Pointer
TO PDF
0
u
1
1
0
u
u
1
Item
RES reset during power-on
RES or LVR reset during normal operation
WDT time-out reset during normal operation
WDT time-out reset during Power Down
RESET Conditions
HT56R66/HT56R666
Reset to zero
All interrupts will be disabled
Clear after reset, WDT begins
counting
The Timer Counter Prescaler
will be cleared
I/O ports will be setup as inputs
Stack Pointer will point to the
top of the stack
Condition After RESET
September 8, 2009