ht82m99e Holtek Semiconductor Inc., ht82m99e Datasheet - Page 12

• Manufacturer Part Number: ht82m99e
• Description: Ht82m99e/ht82m99a -- Usb Mouse Encoder 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

the actual interrupt subroutine execution will be delayed
by one or more cycles. If the wake-up results in the next
instruction execution, this will be executed immediately
after the dummy period is finished.
To minimize power consumption, all the I/O pins should
be carefully managed before entering the HALT status.
Reset
There are four 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 Stack
Pointer, leaving the other circuits in their original state.
Some registers remain unchanged during other reset
conditions. Most registers are reset to the initial condi-
tion when the reset conditions are met. By examining
the PDF and TO flags, the program can distinguish be-
tween different chip resets .
Note: u stands for unchanged
To guarantee that the system oscillator is started and
stabilized, the SST (System Start-up Timer) provides an
extra delay of 1024 system clock pulses when the sys-
tem resets (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.
Rev. 2.20
RES reset during normal operation
RES reset during HALT
WDT time-out reset during normal operation
USB reset
TO
0
u
0
1
1
PDF
0
u
0
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 Circuit
RESET Conditions
12
The functional unit chip reset status are shown below.
Program Counter
Interrupt
Prescaler
WDT
Timer/event Counter Off
Input/output Ports
Stack Pointer
Reset Configuration
Reset Timing Chart
HT82M99E/HT82M99A
000H
Disable
Clear
Clear. After master reset, WDT
begins counting
Input mode
Points to the top of the stack
April 16, 2008