HT66FW2230 Datasheet, PDF (44/148 Pages) Holtek Semiconductor Inc – Wireless Charger A/D Flash MCU

HT66FW2230
Wireless Charger A/D Flash MCU
WDTC
Register
WE4~WE0 bits
“HALT”Instruction
“CLR WDT”Instruction
f_SUB
CLR
Reset MCU
f_SUB/2⁸
8-stage Divider
WDT Prescaler
WS2~WS0
Watchdog Timer
8-to-1 MUX
WDT Time-out
(2⁸/f_SUB ~ 2¹⁸/f_SUB)
Reset and Initialisation
A reset function is a fundamental part of any microcontroller ensuring that the device can be set
to some predetermined condition irrespective of outside parameters. There is a number of other
hardware and software reset sources that can be implemented dynamically when the device is
running.
Reset Overview
The most important reset condition is after power is first applied to the microcontroller. In this case,
internal circuitry will ensure that the microcontroller, after a short delay, will be in a well defined
state and ready to execute the first program instruction. After this power-on reset, certain important
internal registers will be set to defined states before the program commences. One of these registers
is the Program Counter, which will be reset to zero forcing the microcontroller to begin program
execution from the lowest Program Memory address.
The device provides several reset sources to generate the internal reset signal, providing extended
MCU protection. The different types of resets are listed in the accompanying table.
Reset Name
Power-On Reset
RSTC Register Setting
Software Reset
Low-Voltage Reset
Watchdog Reset
WDTC Register Setting
Software Reset
MCD Reset
Abbreviation Indication Bit Register
Notes
POR
—
—
Auto generated at power on
—
ERSTF
RSTFC Write to RSTC register
LVR
WDT
LRF
RSTFC Low VDD voltage
TO
STATUS WDT Time-out
—
WRF
RSTFC Write to WDTC register
—
—
—
Missing Clock Detector
Another type of reset is when the Watchdog Timer overflows and resets the microcontroller. All
types of reset operations result in different register conditions being setup. Another reset exists in
the form of a Low Voltage Reset which is implemented in situations where the power supply voltage
falls below a certain threshold.
Rev. 1.20
44
January 3, 2017