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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262-004US
755
Universal Asynchronous Receiver-Transmitter (UART)—Intel
®
IXP45X and Intel
®
IXP46X
Product Line of Network Processors
shows the serial output data configurations for transmission of the parity bit.
shows the serial input data configurations for reception of data containing a
parity bit.
The Stop-Bits Bit (STB) configures the number of stop bits to be transmitted or
received in each serial character. When the Stop-Bits Bit is logic 0, one stop bit is
generated in the transmitted data. When the Stop-Bits Bit is logic 1, and a 5-bit word
length is selected — via the Word Length select bits in the Line Control Register — 1.5
stop bits will be transmitted.
When the Stop-Bits Bit is logic 1 and the word length is selected as a 6, 7, or 8-bit
word, 2 stop bits are transmitted. The UART receiver logic checks the first stop bit only,
regardless of the number of stop bits configured by the Stop Bits bit.
The Word-Length Select (WLS) Bits specify the number of data bits contained in each
transmitted or received serial character. The Word-Length Select Bits configuration is
shown in
.
The Line-Control Register is initialized to hexadecimal 0x00 after reset. The Line-Status
Register is initialized to hexadecimal 0x60 after reset.
Table 245.
UART Transmit Parity Operation
PEN
EPS
Data to be Transmitted
(Even or Odd Count of 1s to be Transmitted)
Value of Parity Bit to be
Transmitted
1
0
10101010
1
1
0
10101011
0
1
1
10101010
0
1
1
10101011
1
0
X
XXXXXXXX
No Parity Bit Sent
Table 246.
UART Receive Parity Operation
PEN
EPS
Data beIng Re Parity Bit
(Even or Odd Count of 1s to be Transmitted)
Value of Parity Bit Should Be
1
0
101010101
1
1
0
101010110
0
1
1
101010100
0
1
1
101010111
1
0
X
XXXXXXXX
Parity Checking Disabled
Table 247.
UART Word-Length Select Configuration
WLS
Number of Data Bits Contained in Each Transmitted Or Received Character
Bit 1
Bit 0
0
0
5-bit character (default)
0
1
6-bit character
1
0
7-bit character
1
1
8-bit character