HT45R35V Holtek Semiconductor Inc., HT45R35V Datasheet - Page 16

• Manufacturer Part Number: HT45R35V
• Description: C/r To F Type 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

Reset
There are three ways in which a reset can occur:
A WDT time-out, when the device is in the Power Down
mode, is different from other device reset conditions, in
that it can perform a warm reset that resets only the
Program Counter and the Stack Poiner, leaving the
other circuits in their original state. Some registers re-
main unchanged during other reset conditions. Most
registers are reset to their initial condition when the re-
set conditions are met. By examining the PDF and TO
flags, the program can distinguish between the different
device reset types.
Note: u means unchanged
To guarantee that the system oscillator is started and
stabilised, the SST or System Start-up Timer, provides
an extra-delay of 1024 system clock pulses when the
system is reset (power-up, WDT time-out or RES reset)
or when the system awakens from a Power Down state.
When a system reset occurs, the SST delay is added
during the reset period. Any wake-up the Power Down
mode will enable the SST delay.
An extra option load time delay is added during a system
reset (power-up, WDT time-out during normal mode or a
RES reset).
Rev. 1.00
RES reset during normal operation
RES reset during HALT
WDT time-out reset during normal operation
TO
0
u
0
1
1
PDF
0
u
1
u
1
RES reset during power-up
RES reset during normal operation
RES wake-up HALT
WDT time-out during normal operation
WDT wake-up HALT
Reset Timing Chart
RESET Conditions
16
Note:
The functional unit device reset status are shown below.
Program Counter
Interrupt
Prescaler
WDT
Timer/Event Counter Off
Input/Output Ports
Stack Pointer
m
W
Most applications can use the Basic Reset Cir-
cuit as shown, however for applications with ex-
tensive noise, it is recommended to use the
Hi-noise Reset Circuit.
Reset Configuration
Reset Circuit
000H
Disable
Clear
Clear. After master reset,
WDT begins counting
Input mode
Points to the top of the stack
m
W
W
January 15, 2009
HT45R35V
m