Rev. 1.00
58
September 11, 2018
Rev. 1.00
59
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
• RSTC Register
Bit
7
6
5
4
3
2
1
0
Name
RSTC7
RSTC6
RSTC5
RSTC4
RSTC3
RSTC2
RSTC1
RSTC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
1
0
1
0
1
0
1
Bit 7~0
RSTC7~RSTC0
: Reset function control
01010101: PB5
10101010:
RES
pin
O
ther values: Reset MCU
If these bits are changed due to adverse environmental conditions, the microcontroller
will be reset. The reset operation will be activated after a delay time, t
SRESET
, and the
RSTF bit in the RSTFC register will be set to 1.
All resets will reset this register to POR value except the WDT time out hardware
warm reset. Note that when if this register is set to 10101010B to select the RES
pin
function, this configuration has higher priority than other related pin-shared controls.
• RSTFC Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
—
—
RSTF
LVRF
LRF
WRF
R/W
—
—
—
—
R/W
R/W
R/W
R/W
POR
—
—
—
—
0
x
0
0
"x": unknown
Bit 7~4
Unimplemented, read as "0"
Bit 3
RSTF
: Reset control register software reset flag
0: Not occurred
1: Occurred
This bit is set to 1 by the RSTC control register software reset and cleared by the
application program. Note that this bit can only be cleared to 0 by the application
program.
Bit 2
LVRF
: LVR function reset flag
Refer to the Low Voltage Reset section.
Bit 1
LRF
: LVR control register software reset flag
Refer to the Low Voltage Reset section.
Bit 0
WRF
: WDT control register software reset flag
Refer to the Watchdog Timer Control Register section.
Low Voltage Reset – LVR
The microcontroller contains a low voltage reset circuit in order to monitor the supply voltage of the
device. The LVR function is always enabled with a specific LVR voltage V
LVR
. If the supply voltage
of the device drops to within a range of 0.9V~V
LVR
such as might occur when changing the battery,
the LVR will automatically reset the device internally and the LVRF bit in the RSTFC register will
also be set to 1. For a valid LVR signal, a low supply voltage, i.e., a voltage in the range between
0.9V~V
LVR
must exist for a time greater than that specified by t
LVR
in the LVD & LVR Electrical
Characteristics. If the low supply voltage state does not exceed this value, the LVR will ignore the
low supply voltage and will not perform a reset function. The actual V
LVR
value can be selected by
the LVS bits in the LVRC register. If the LVS7~LVS0 bits are changed to some certain values by
the environmental noise or software setting, the LVR will reset the device after a delay time,
t
SRESET
.
When this happens, the LRF bit in the RSTFC register will be set to 1. After power on the register
will have the value of
01100110B
. Note that the LVR function will be automatically disabled when
the device enters the
IDLE or SLEEP
mode.