xr17c152im Exar Corporation, xr17c152im Datasheet - Page 39

• Manufacturer Part Number: xr17c152im
• Description: 5v Pci Bus Dual Uart
• Manufacturer: Exar Corporation

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REV. 1.2.0
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.
LCR[5]: TX and RX Parity Select
If the parity bit is enabled, LCR BIT-5 selects the forced parity format.
4.8.7
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.
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 (default).
Logic 1 = EVEN Parity is generated by forcing an even the number of logic 1’s in the transmitted character.
The receiver must be programmed to check the same format.
LCR BIT-5 = logic 0, parity is not forced (default).
LCR BIT-5 = logic 1 and LCR BIT-4 = logic 0, parity bit is forced to a logical 1 for the transmit and receive
data.
LCR BIT-5 = logic 1 and LCR BIT-4 = logic 1, parity bit is forced to a logical 0 for the transmit and receive
data.
Line Control Register (LCR) - Read/Write
Table 15
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
39
S
W
TOP BIT LENGTH
(B
ORD LENGTH
5 (default)
1 (default)
IT TIME
1-1/2
6
7
8
2
(
S
))
5V PCI BUS DUAL UART
XR17C152