C8051F124-GQR Datasheet, PDF (296/350 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 21.1. SCON0: UART0 Control
R/W
SM00
Bit7
R/W
SM10
Bit6
R/W
SM20
Bit5
R/W
REN0
Bit4
R/W
TB80
Bit3
R/W
RB80
Bit2
R/W
R/W
Reset Value
TI0
RI0 00000000
Bit1
Bit0
Bit
Addressable
SFR Address: 0x98
SFR Page: 0
Bits7–6: SM00–SM10: Serial Port Operation Mode:
Write:
When written, these bits select the Serial Port Operation Mode as follows:
SM00
0
0
1
1
SM10
0
1
0
1
Mode
Mode 0: Synchronous Mode
Mode 1: 8-Bit UART, Variable Baud Rate
Mode 2: 9-Bit UART, Fixed Baud Rate
Mode 3: 9-Bit UART, Variable Baud Rate
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
Reading these bits returns the current UART0 mode as defined above.
SM20: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port Operation Mode.
Mode 0: No effect
Mode 1: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
Mode 2 and 3: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1 and the
received address matches the UART0 address or the broadcast address.
REN0: Receive Enable.
This bit enables/disables the UART0 receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in Modes 2 and 3. It is
not used in Modes 0 and 1. Set or cleared by software as required.
RB80: Ninth Receive Bit.
The bit is assigned the logic level of the ninth bit received in Modes 2 and 3. In Mode 1, if
SM20 is logic 0, RB80 is assigned the logic level of the received stop bit. RB8 is not used in
Mode 0.
TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in
Mode 0, or at the beginning of the stop bit in other modes). When the UART0 interrupt is
enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine.
This bit must be cleared manually by software
RI0: Receive Interrupt Flag.
Set by hardware when a byte of data has been received by UART0 (as selected by the
SM20 bit). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector
to the UART0 interrupt service routine. This bit must be cleared manually by software.
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Rev. 1.4