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Table 13. Line Control Register (LCR) Field Descriptions (continued)
Bit Field Value Description
2 STB Number of STOP bits generated. STB specifies 1, 1.5, or 2 STOP bits in each transmitted character.
When STB = 1, the WLS bit determines the number of STOP bits. The receiver clocks only the first
STOP bit, regardless of the number of STOP bits selected. The number of STOP bits generated is
summarized in Table 15.
0 1 STOP bit is generated.
1 WLS bit determines the number of STOP bits:
• When WLS = 0, 1.5 STOP bits are generated.
• When WLS = 1h, 2h, or 3h, 2 STOP bits are generated.
1-0 WLS 0-3h Word length select. Number of bits in each transmitted or received serial character. When STB = 1, the
WLS bit determines the number of STOP bits.
0 5 bits
1h 6 bits
2h 7 bits
3h 8 bits
Table 14. Relationship Between ST, EPS, and PEN Bits in LCR
ST Bit EPS Bit PEN Bit Parity Option
x x 0 Parity disabled: No PARITY bit is transmitted or checked
0 0 1 Odd parity selected: Odd number of logic 1s
0 1 1 Even parity selected: Even number of logic 1s
1 0 1 Stick parity selected with PARITY bit transmitted and checked as set
1 1 1 Stick parity selected with PARITY bit transmitted and checked as cleared
Table 15. Number of STOP Bits Generated
Word Length Selected Number of STOP Bits Baud Clock (BCLK)
STB Bit WLS Bits with WLS Bits Generated Cycles
0 x Any word length 1 16
1 0h 5 bits 1.5 24
1 1h 6 bits 2 32
1 2h 7 bits 2 32
1 3h 8 bits 2 32
29
SPRU997C–December 2009 Universal Asynchronous Receiver/Transmitter (UART)
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