SCON Register in 8051

The serial control register is an 8-bit register and its address is 0X98.  it can be Bit and Byte Addressable. the serial control register is used to configure and control serial port.

R1 -

Set, to indicate a byte has been received by 8051 and placed in SBUF.

T1 -

Set, when 8051 finishes transfer of 8-bit character.

RB8 -

Receive bit 8. This is the 9th bit received in modes 2 .and 3. If  SM2=0, RB8 is the stop bit.

TB8 -

Transmit bit 8. This is the 9th bit transmitted in modes 2 and 3.

REN -

Receiver enable/disable bit. Set HIGH to receive data on the RxD pin.

SM2 -

Enables multiprocessor communication in modes 2 and 3. In mode 2 or 3, if SM2 is set to 1 then RI will not be activated if the received 9th data bit (RB8) is 0. In mode 1, if SM2=1 then RI will not be activated if a valid stop bit was not received. In mode 0, SM2 should be 0.

SM1 -

This is the serial mode selection bit as shown below.

SM0 -

This is the serial mode selection bit as shown below.