
Rev. 1.00
152
October 26, 2018
Rev. 1.00
153
October 26, 2018
BS86DH12C
High Voltage Touch A/D Flash MCU with HVIO
BS86DH12C
High Voltage Touch A/D Flash MCU with HVIO
The UART function contains a receiver RX pin wake-up function, which is enabled or disabled
by the WAKE bit in the UCR2 register. If this bit, along with the UART enable bit, UARTEN, the
receiver enable bit, RXEN and the receiver interrupt bit, RIE, are all set when the UART clock (f
H
)
is off, then a falling edge on the RX pin will trigger an RX pin wake-up UART interrupt. Note that
as it takes certain system clock cycles after a wake-up, before normal microcontroller operation
resumes, any data received during this time on the RX pin will be ignored.
For a UART wake-up interrupt to occur, in addition to the bits for the wake-up being set, the global
interrupt enable bit, EMI, and the UART interrupt enable bit, URE, must be set. If the EMI and URE
bits are not set then only a wake up event will occur and no interrupt will be generated. Note also
that as it takes certain system clock cycles after a wake-up before normal microcontroller resumes,
the UART interrupt will not be generated until after this time has elapsed.
Low Voltage Detector – LVD
The device has a Low Voltage Detector function, also known as LVD. This enables the device to
monitor the power supply voltage, V
DD
, and provide a warning signal should it fall below a certain
level. This function may be especially useful in battery applications where the supply voltage will
gradually reduce as the battery ages, as it allows an early warning battery low signal to be generated.
The Low Voltage Detector also has the capability of generating an interrupt signal.
LVD Register
The Low Voltage Detector function is controlled using a single register with the name LVDC. Three
bits in this register, VLVD2~VLVD0, are used to select one of eight fixed voltages below which
a low voltage condition will be determined. A low voltage condition is indicated when the LVDO
bit is set. If the LVDO bit is low, this indicates that the V
DD
voltage is above the preset low voltage
value. The LVDEN bit is used to control the overall on/off function of the low voltage detector.
Setting the bit high will enable the low voltage detector. Clearing the bit to zero will switch off the
internal low voltage detector circuits. As the low voltage detector will consume a certain amount of
power, it may be desirable to switch off the circuit when not in use, an important consideration in
power sensitive battery powered applications.
• LVDC Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
LVDO
LVDEN
VBGEN
VLVD2
VLVD1
VLVD0
R/W
—
—
R
R/W
R/W
R/W
R/W
R/W
POR
—
—
0
0
0
0
0
0
Bit 7~6
Unimplemented, read as “0”
Bit 5
LVDO
: LVD Output Flag
0: No Low Voltage Detect
1: Low Voltage Detect
Bit 4
LVDEN
: Low Voltage Detector Control
0: Disable
1: Enable
Bit 3
VBGEN
: Bandgap Buffer Control
0: Disable
1: Enable
Note that the Bandgap circuit is enabled when the LVD or LVR function is enabled or
when the VBGEN bit is set to 1.