HT46R064D/065D/066D
Enhanced A/D Type 8-Bit OTP MCU with LED Driver
the device enters the Sleep Mode. To keep the LXT power consumption to a minimum level the
LXTLP bit in the CTRL0 register, which controls the low power function, should be set high.
Wake-up
After the system enters the Sleep Mode, it can be woken up from one of various sources listed as
follows:
·
An external reset
·
·
·
An external falling edge on PA0 to PA7
A system interrupt
A WDT overflow
If the system is woken up by an external reset, the device will experience a full system reset, how-
ever, if the device is woken up by a WDT overflow, a Watchdog Timer reset will be initiated. Al-
though both of these wake-up methods will initiate a reset operation, the actual source of the
wake-up can be determined by examining the TO and PDF flags. The PDF flag is cleared by a sys-
tem power-up or executing the clear Watchdog Timer instructions and is set when executing the
²HALT² instruction. The TO flag is set if a WDT time-out occurs, and causes a wake-up that only re-
sets the Program Counter and Stack Pointer, the other flags remain in their original status.
Pins PA0 to PA7 can be setup via the PAWUK register to permit a negative transition on the pin to
wake-up the system. When a PA0 to PA7 pin wake-up occurs, the program will resume execution at the
instruction following the ²HALT² instruction.
If the system is woken up by an interrupt, then two possible situations may occur. The first is where the
related interrupt is disabled or the interrupt is enabled but the stack is full, in which case the program
will resume execution at the instruction following the ²HALT² instruction. In this situation, the
interrupt which woke-up the device will not be immediately serviced, but will rather be serviced later
when the related interrupt is finally enabled or when a stack level becomes free. The other situation is
where the related interrupt is enabled and the stack is not full, in which case the regular interrupt
response takes place. If an interrupt request flag is set to ²1² before entering the Sleep Mode, then any
future interrupt requests will not generate a wake-up function of the related interrupt will be ignored.
No matter what the source of the wake-up event is, once a wake-up event occurs, there will be a time
delay before normal program execution resumes. Consult the table for the related time.
Oscillator Type
Wake-up
Source
ERC, IRC
Crystal
External RES
PA Port
tRSDT + tSST2
tRSDT + tSST2
tSST1
tSST2
Interrupt
WDT Overflow
Note: 1. tRSTD (reset delay time), tSYS (system clock)
2. tRSTD is power-on delay, typical time=50ms
3. tSST1= 2 tSYS
4. tSST2= 128 tSYS
Wake-up Delay Time
Rev. 1.00
32
January 12, 2011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
