Rev. 1.10
172
October 23, 2020
Rev. 1.10
173
October 23, 2020
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
Address Detect Mode
Setting the Address Detect Mode bit, ADDEN, in the UCR2 register, enables this special mode. If
this bit is enabled then an additional qualifier will be placed on the generation of a Receiver Data
Available interrupt, which is requested by the RXIF flag. If the ADDEN bit is enabled, then when
data is available, an interrupt will only be generated, if the highest received bit has a high value. Note
that the URE and EMI interrupt enable bits must also be enabled for correct interrupt generation.
This highest address bit is the 9th bit if BNO=1 or the 8th bit if BNO=0. If this bit is high, then
the received word will be defined as an address rather than data. A Data Available interrupt will be
generated every time the last bit of the received word is set. If the ADDEN bit is not enabled, then
a Receiver Data Available interrupt will be generated each time the RXIF flag is set, irrespective of
the data last bit status. The address detect mode and parity enable are mutually exclusive functions.
Therefore if the address detect mode is enabled, then to ensure correct operation, the parity function
should be disabled by resetting the parity enable bit PREN to zero.
ADDEN
Bit 9 if BNO=1
Bit 8 if BNO=0
UART Interrupt
Generated
0
0
√
1
√
1
0
×
1
√
ADDEN Bit Function
UART Power Down and Wake-up
When the UART clock, f
H
, is switched off, the UART will cease to function. If the MCU switches
off the UART clock, f
H
, and enters the power down mode while a transmission is still in progress,
then the transmission will be paused until the UART clock source derived from the microcontroller
is activated. In a similar way, if the MCU switches off the UART clock f
H
and enters the IDLE
or SLEEP mode by executing the “HALT” instruction while receiving data, then the reception of
data will likewise be paused. When the MCU enters the IDLE or SLEEP mode, note that the USR,
UCR1, UCR2, transmit and receive registers, as well as the BRG register will not be affected. It is
recommended to make sure first that the UART data transmission or reception has been finished
before the microcontroller enters the IDLE or SLEEP mode.
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 MCU enters the
power down mode with the UART clock f
H
being switched 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.