xr20v2172 Exar Corporation, xr20v2172 Datasheet - Page 28

• Manufacturer Part Number: xr20v2172
• Description: Two Channel I2c/spi Uart With 64-byte Fifo And Rs232 Transceiver
• Manufacturer: Exar Corporation

XR20V2172
TWO CHANNEL I2C/SPI UART WITH 64-BYTE FIFO AND RS232 TRANSCEIVER
The Line Control Register is used to specify the asynchronous data communication format. The word or
character length, the number of stop bits, and the parity are selected by writing the appropriate bits in this
register.
LCR[1:0]: TX and RX Word Length Select
These two bits specify the word length to be transmitted or received.
LCR[2]: TX and RX Stop-bit Length Select
The length of stop bit is specified by this bit in conjunction with the programmed word length.
LCR[3]: TX and RX Parity Select
Parity or no parity can be selected via this bit. The parity bit is a simple way used in communications for data
integrity check. See
•
•
LCR[4]: TX and RX Parity Select
If the parity bit is enabled with LCR bit-3 set to a logic 1, LCR bit-4 selects the even or odd parity format.
•
•
4.6
Logic 0 = No parity.
Logic 1 = A parity bit is generated during the transmission while the receiver checks for parity error of the
data character received (default).
Logic 0 = ODD Parity is generated by forcing an odd number of logic 1’s in the transmitted character. The
receiver must be programmed to check the same format.
Logic 1 = EVEN Parity is generated by forcing an even number of logic 1’s in the transmitted character. The
receiver must be programmed to check the same format (default).
Line Control Register (LCR) - Read/Write
Table 11
for parity selection summary below.
BIT-1
BIT-2
0
0
1
1
0
1
1
LENGTH
BIT-0
5,6,7,8
W
6,7,8
0
1
0
1
ORD
5
28
S
W
TOP BIT LENGTH
(B
ORD LENGTH
6 (default)
2 (default)
IT TIME
1-1/2
5
7
8
1
(
S
))
REV. 1.0.0