LS_Universal asynchronous receiver/transmitter (UART)
RM0082
600/844
Doc ID 018672 Rev 1
Note:
UARTLCR_H, UARTIBRD and UARTFBRD form a single 30 bit wide register named
UARTLCR, which is updated on a single write strobe generated by a UARTLCR_H write. So,
in order to internally update the contents of the UARTIBRD or UARTFBRD registers, a write
to UARTLCR_H must always be performed at the end.
[06:05]
WLEN
2’h0
Word length.
This 2 bit field indicates the number of data bits transmitted or
received in a frame, according to encoding:
– 2‘b00 = 5
– 2‘b01 = 6
– 2‘b10 = 7
– 2‘b11 = 8
[04]
FEN
1’h0
Enable FIFOs.
Setting this bit, transmit and receive FIFO buffers are enabled.
In contrast (FEN cleared), the FIFOs are disabled becoming 1-
byte-deep holding registers.
[03]
STP2
1’h0
Two stop bit select.
Setting this bit, two stop bits are transmitted at the end of the
frame. The receive logic does not check for two stop bits being
received.
[02]
EPS
1’h0
Even parity select.
This bit allows to select either an even or an odd parity
generation and checking during transmission and reception,
which checks for an even or an odd number of 1s in data and
parity bits, according to encoding:
1‘b0 = Odd
1‘b1 = Even
Note: This bit has no effect when parity is disabled by clearing
Parity Enable bit (PEN in this register).
[01]
PEN
1’h0
Parity enable.
Setting this bit, parity checking and generation is enabled,
otherwise (PEN set to 1‘b0) parity is disabled and no parity bit
is added to the data frame.
[00]
BRK
1’h0
Send break.
Setting this bit, a low-level is continually output on the
UARTTXD output after completing transmission of the current
character. For proper execution of the break command, the
software must set this bit for at least two complete frames.
Table 528.
UARTLCR_H register bit assignments (continued)
Bit
Name
Reset value Description
Table 529.
Truth table for SPS, EPS and PEN bits
Pen
Eps
Sps
Parity bit
1‘b0
X
X
Not transmitted or checked.
1‘b1
1‘b1
1‘b0
Even parity.
1‘b1
1‘b0
1‘b0
Odd parity.