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USART Registers
U1CSR (0xF8)
–
USART 1 Control and Status
Bit
Name
Reset
R/W
Description
7
MODE
0
R/W
USART mode select
0:
SPI mode
1:
UART mode
6
RE
0
R/W
UART receiver enable. Note: Do not enable receive before UART is fully configured.
0:
Receiver disabled
1:
Receiver enabled
5
SLAVE
0
R/W
SPI master- or slave-mode select
0:
SPI master
1:
SPI slave
4
FE
0
R/W0
UART framing error status. This bit is automatically cleared on a read of the
U1CSR
register or bits
in the
U1CSR
register.
0:
No framing error detected
1:
Byte received with incorrect stop-bit level
3
ERR
0
R/W0
UART parity error status. This bit is automatically cleared on a read of the
U1CSR
register or bits in
the
U1CSR
register.
0:
No parity error detected
1:
Byte received with parity error
2
RX_BYTE
0
R/W0
Receive byte status. UART mode and SPI slave mode. This bit is automatically cleared when
reading
U1DBUF
; clearing this bit by writing 0 to it effectively discards the data in
U1DBUF
.
0:
No byte received
1:
Received byte ready
1
TX_BYTE
0
R/W0
Transmit byte status. UART mode and SPI master mode
0:
Byte not transmitted
1:
Last byte written to data buffer register has been transmitted
0
ACTIVE
0
R
USART transmit/receive active status. In SPI slave mode, this bit equals slave select.
0:
USART idle
1:
USART busy in transmit or receive mode
U1UCR (0xFB)
–
USART 1 UART Control
Bit
Name
Reset
R/W
Description
7
FLUSH
0
R0/W1
Flush unit. When set, this event stops the current operation and returns the unit to the idle state.
6
FLOW
0
R/W
UART hardware flow enable. Selects use of hardware flow control with RTS and CTS pins
0:
Flow control disabled
1:
Flow control enabled
5
D9
0
R/W
If parity is enabled (see
PARITY
, bit 3 in this register), then this bit sets the parity level as follows.
0:
Odd parity
1:
Even parity
4
BIT9
0
R/W
Set this bit to 1 in order to enable the parity bit tranfer (as 9th bit). The content of this 9th bit is given
by
D9
, if parity is enabled by
PARITY
.
0:
8-bit transfer
1:
9-bit transfer
3
PARITY
0
R/W
UART parity enable. One must set
BIT9
in addition to setting this bit for parity to be calculated.
0:
Parity disabled
1:
Parity enabled
2
SPB
0
R/W
UART number of stop bits. Selects the number of stop bits to transmit
0:
1 stop bit
1:
2 stop bits
1
STOP
1
R/W
UART stop-bit level must be different from start-bit level.
0:
Low stop bit
1:
High stop bit
0
START
0
R/W
UART start-bit level. Ensure that the polarity of the start bit is opposite the level of the idle line.
0:
Low start bit
1:
High start bit
170
USART
SWRU191C
–
April 2009
–
Revised January 2012
Copyright
©
2009
–
2012, Texas Instruments Incorporated