ht82m9aae Holtek Semiconductor Inc., ht82m9aae Datasheet - Page 13

• Manufacturer Part Number: ht82m9aae
• Description: Usb Mouse Encoder 8-bit Mcu With Eeprom
• Manufacturer: Holtek Semiconductor Inc.

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 ²warm re -
set² that resets only the program counterand SP, leaving
the other circuits in their original state. Some registers
remain unchanged during other reset conditions. Most
registers are reset to the ²initial condition² when the re-
set conditions are met. By examining the PDF and TO
flags, the program can distinguish between different
²chip resets².
Note: ²u² stands for ²unchanged²
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. 1.20
TO PDF
RES reset during normal operation
RES reset during HALT
WDT time-out reset during normal operation
USB reset
0
u
0
1
1
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 Timing Chart
RESET Conditions
13
The functional unit chip reset status are shown below.
Program Counter
Interrupt
Prescaler
WDT
Timer/event Counter Off
Input/output Ports
Stack Pointer
HT82M9AEE/HT82M9AAE
Reset Configuration
Reset Circuit
000H
Disable
Clear
Clear. After master reset,
WDT begins counting
Input mode
Points to the top of the stack
August 13, 2007