C8051F120/1/2/3/4/5/6/7 C8051F130/1/2/3
296
Rev. 1.4
SFR Definition 21.1. SCON0: UART0 Control
Bits7–6: SM00–SM10: Serial Port Operation Mode:
Write:
When written, these bits select the Serial Port Operation Mode as follows:
Reading these bits returns the current UART0 mode as defined above.
Bit5:
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.
Bit4:
REN0: Receive Enable.
This bit enables/disables the UART0 receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
Bit3:
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.
Bit2:
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.
Bit1:
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
Bit0:
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.
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SM00
SM10
SM20
REN0
TB80
RB80
TI0
RI0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address:
SFR Page:
0x98
0
SM00
SM10
Mode
0
0
Mode 0: Synchronous Mode
0
1
Mode 1: 8-Bit UART, Variable Baud Rate
1
0
Mode 2: 9-Bit UART, Fixed Baud Rate
1
1
Mode 3: 9-Bit UART, Variable Baud Rate
Summary of Contents for C8051F12 Series
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