Rev. 1.20
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Rev. 1.20
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BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
000:2
8
/f
SUB
WS[2:0]=
f
SUB
CLR
Reset
MCU
11 stage divide�
8-to-1 MUX
WDT Time-o�t
WS2~WS0
7-stage Divide�
(f
SUB
/2
1
~f
SUB
/2
11
)
001:2
10
/f
SUB
010:2
12
/f
SUB
011:2
14
/f
SUB
100:2
1�
/f
SUB
101:2
16
/f
SUB
110:2
17
/f
SUB
111:2
18
/f
SUB
“
HALT
”
Inst��ction
“
CLR WDT
”
Inst��ction
WE4~WE0 bits
WDTC Registe�
LIRC
LXT
M
U
X
Config��ation
Option
Note: For the BS82B12A-3 device, the f
SUB
is supplied only by the LIRC oscillator.
Watchdog Timer
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. 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.
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, LVR, where a full reset, is implemented in situations where the power
supply voltage falls below a certain threshold.
Reset Functions
There are several ways in which a microcontroller reset can occur, through events occurring internally:
Power-on Reset
The most fundamental and unavoidable reset is the one that occurs after power is first applied to
the microcontroller. As well as ensuring that the Program Memory begins execution from the first
memory address, a power-on reset also ensures that certain other registers are preset to known
conditions. All the I/O port and port control registers will power up in a high condition ensuring that
all pins will be first set to inputs.
VDD
Powe�-on
Reset
SST Time-o�t
t
RSTD
Note: t
RSTD
is power-on delay, typical time=50ms
Power-On Reset Timing Chart
Содержание BS82B12A-3
Страница 33: ...Rev 1 20 33 January 23 2015 BS82B12A 3 BS82C16A 3 BS82D20A 3 Touch Key 8 Bit Flash MCU with LED LCD Driver ...
Страница 34: ...Rev 1 20 34 January 23 2015 BS82B12A 3 BS82C16A 3 BS82D20A 3 Touch Key 8 Bit Flash MCU with LED LCD Driver ...
Страница 35: ...Rev 1 20 35 January 23 2015 BS82B12A 3 BS82C16A 3 BS82D20A 3 Touch Key 8 Bit Flash MCU with LED LCD Driver ...