HT46RU66 Holtek Semiconductor Inc., HT46RU66 Datasheet - Page 17

• Manufacturer Part Number: HT46RU66
• Description: Ht46ru66/ht46cu66 -- A/d Type 8-bit Mcu With Lcd
• Manufacturer: Holtek Semiconductor Inc.

Reset
There are several ways in which a reset may occur.
A WDT time-out when the device is in the Power Down
mode differs from the other reset conditions, as it per-
forms a warm reset that resets only the program coun-
ter and SP and leaves the other circuits in their original
state. Some registers remain unaffected during the
other reset conditions. Most registers are reset to their
initial condition once the reset conditions are met. By ex-
amining the PDF and TO flags, the program can distin-
guish between the different types of resets.
Note: u stands for unchanged
To guarantee that the system oscillator has started and
stabilized, the SST (System Start-up Timer) provides an
extra delay of 1024 system clock pulses when the sys-
tem awakens from the Power Down mode or during
power up.
Rev. 1.20
TO PDF
RES is reset during normal operation
Power on reset
RES is reset during a Power Down
WDT time-out is reset during normal operation
WDT time-out during a Power Down
0
u
0
1
1
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
17
Note:
The functional unit chip reset status is shown below.
Program Counter
Interrupt
Prescaler, Divider
WDT, RTC,
Time Base
Timer/event Counter Off
Input/output Ports
Stack Pointer
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
HT46RU66/HT46CU66
Reset Circuit
000H
Disabled
Cleared
Cleared. After a master reset,
the WDT starts counting
Input mode
Points to the top of the stack
October 2, 2007