MEC1404 Datasheet, PDF (285/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
17.11.8 LINE CONTROL REGISTER
Offset 03h
Bits
Description
Type
7 DLAB
R/W
Divisor Latch Access Bit (DLAB). It must be set high (logic “1”) to
access the Divisor Latches of the Baud Rate Generator during
read or write operations. It must be set low (logic “0”) to access the
Receiver Buffer Register, the Transmitter Holding Register, or the
Interrupt Enable Register.
6 BREAK_CONTROL
R/W
Set Break Control bit. When bit 6 is a logic “1”, the transmit data
output (TXD) is forced to the Spacing or logic “0” state and remains
there (until reset by a low level bit 6) regardless of other transmitter
activity. This feature enables the Serial Port to alert a terminal in a
communications system.
5 STICK_PARITY
R/W
Stick Parity bit. When parity is enabled it is used in conjunction with
bit 4 to select Mark or Space Parity. When LCR bits 3, 4 and 5 are
1 the Parity bit is transmitted and checked as a 0 (Space Parity). If
bits 3 and 5 are 1 and bit 4 is a 0, then the Parity bit is transmitted
and checked as 1 (Mark Parity). If bit 5 is 0 Stick Parity is disabled.
Bit 3 is a logic “1” and bit 5 is a logic “1”, the parity bit is transmitted
and then detected by the receiver in the opposite state indicated by
bit 4.
4 PARITY_SELECT
R/W
Even Parity Select bit. When bit 3 is a logic “1” and bit 4 is a logic
“0”, an odd number of logic “1”'s is transmitted or checked in the
data word bits and the parity bit. When bit 3 is a logic “1” and bit 4
is a logic “1” an even number of bits is transmitted and checked.
3 ENABLE_PARITY
R/W
Parity Enable bit. When bit 3 is a logic “1”, a parity bit is gener-
ated (transmit data) or checked (receive data) between the last
data word bit and the first stop bit of the serial data. (The parity bit
is used to generate an even or odd number of 1s when the data
word bits and the parity bit are summed).
2 STOP_BITS
R/W
This bit specifies the number of stop bits in each transmitted or
received serial character. TABLE 17-9: summarizes the informa-
tion.
1:0 WORD_LENGTH
R/W
These two bits specify the number of bits in each transmitted or
received serial character. The encoding of bits 0 and 1 is as fol-
lows:
Default
0h
Reset
Event
RESET
0h
RESET
0h
RESET
0h
RESET
0h
RESET
0h
RESET
0h
RESET
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DS00001956D-page 285