Silicon Laboratories C8051F341, C8051F347 SFR Definition 19.3. SBUF1 UART1 Data Buffer, SB1RUN

C8051F340/1/2/3/4/5/6/7

SFR Definition 19.3. SBUF1: UART1 Data Buffer

R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W	Reset Value
								00000000
Bit7	Bit6	Bit5	Bit4	Bit3	Bit2	Bit1	Bit0

SFR Address: 0xD3

Bits7–0: SBUF1[7:0]: Serial Data Buffer Bits 7–0 (MSB-LSB)

This SFR is used to both send data from the UART and to read received data from the UART1 receive FIFO.

Write: Writing a byte to SBUF1 initiates the transmission. When data is written to SBUF1, it first goes to the Transmit Holding Register, where it is held for serial transmission. When the transmit shift register is available, data is transferred into the shift register, and SBUF1 may be written again.

Read: Reading SBUF1 retrieves data from the receive FIFO. When read, the oldest byte in the receive FIFO is returned, and removed from the FIFO. Up to three bytes may be held in the FIFO. If there are additional bytes available in the FIFO, the RI1 bit will remain at logic ‘1’, even after being cleared by software.

SFR Definition 19.4. SBCON1: UART1 Baud Rate Generator Control

R/W		R/W	R/W	R/W	R/W	R/W	R/W	R/W	Reset Value
Reserved		SB1RUN	Reserved	Reserved	Reserved	Reserved	SB1PS1	SB1PS0	00000000
Bit7		Bit6	Bit5	Bit4	Bit3	Bit2	Bit1	Bit0	Bit
									Addressable
								SFR Address: 0xAC
Bit7:	RESERVED: Read = 0b; Must write 0b.
Bit6:	SB1RUN: Baud Rate Generator Enable.
	0: Baud Rate Generator is disabled. UART1 will not function.
	1: Baud Rate Generator is enabled.
Bits5–2:	RESERVED: Read = 0000b; Must write 0000b.
Bits1–0:	SB1PS[1:0]: Baud Rate Prescaler Select.
	00: Prescaler = 12
	01: Prescaler = 4
	10: Prescaler = 48
	11: Prescaler = 1

226 Rev. 0.5