HT48R03 Holtek Semiconductor, HT48R03 Datasheet - Page 14

• Manufacturer Part Number: HT48R03
• Description: (HT48R01 - HT48R03) 10-Pin MSOP I/O Type 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

tion of the related interrupt will be disabled. Once a
wake-up event occurs, it takes 1024 t
period) to resume normal operation. In other words, a
dummy period will be inserted after wake-up. If the
wake-up results from an interrupt acknowledgment, the
actual interrupt subroutine execution will be delayed by
one or more cycles. If the wake-up results in the next in-
struction execution, this will be executed immediately
after the dummy period is finished.
To minimise power consumption, all the I/O pins should
be carefully managed before entering the HALT status.
Reset
There are three ways in which a reset can occur:
The WDT time-out during HALT is different from other
chip reset conditions, since it can perform a warm re -
set that resets only the Program Counter and SP, leav-
ing the other circuits in their original state. Some regis-
ters remain unchanged during other reset conditions.
Most registers are reset to the initial condition when
the reset conditions are met. By examining the PDF and
TO flags, the program can distinguish between different
Note: u means unchanged
To guarantee that the system oscillator is started and
stabilised, the SST (System Start-up Timer) provides an
extra-delay of 1024 system clock pulses when the sys-
tem reset (power-up, WDT time-out or RES reset) or the
system awakes from the HALT state.
When a system reset occurs, the SST delay is added
during the reset period. Any wake-up from HALT will en-
able the SST delay.
An extra option load time delay is added during a system
reset (power-up, WDT time-out during normal mode or
RES reset).
Rev. 1.00
1 before entering the HALT mode, the wake-up func-
chip resets .
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 Conditions
SYS
(system clock
14
The functional unit chip reset status are shown below.
Note:
Program Counter
Interrupt
Prescaler
WDT
Timer/Event Counter Off
Input/Output Ports
Stack Pointer
nected to the RES pin as short as possible, to
avoid noise interference.
* Make the length of the wiring, which is con-
HT48R01/HT48R02/HT48R03
Reset Configuration
Reset Timing Chart
Reset Circuit
m
W
W
000H
Disable
Clear
Clear. After master reset,
WDT begins counting
Input mode
Points to the top of the stack
m
December 20, 2006