LS_Universal asynchronous receiver/transmitter (UART)
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Doc ID 018672 Rev 1
register (bottom word of the transmit FIFO). The write operation initiates transmission from
the UART. The data is prefixed with a start bit, appended with the parity bit (if enabled) and
a stop bit. The resultant word is then transmitted.
For received words, if FIFOs are enabled, the data byte and the 4 bit status (break, frame,
parity and overrun) is pushed into the 12 bit receive FIFO. If FIFOs are not enabled, data
byte and status are stored in the receiving holding register (bottom word of the receive
FIFO).
The UARTDR bit assignments are given in
27.4.2 UARTRSR/UARTECR
register
The UARTRSR/UARTECR (receive status/error clear) is a unique 8 bit RW register which
allows to manage the function of both receive status and error clear register.
UARTRSR is intended for reading only to give the status information for break, framing and
priority corresponds to the data character read from UARTDR (
) prior to
reading UARTRSR. The status information for overrun is set immediately when an overrun
condition occurs. The UARTRSR bit assignments are given in
.
In contrast, a write to UARTECR clears the framing, parity, break and overrun errors. The
data value is not important. The UARTECR bit assignments are given in
.
Note:
The received data character must be read first from UARTDR before reading the error status
associated with the data character from UARTRSR. This read sequence cannot be reversed
because UARTRSR is updated only when a read occurs from UARTDR. However, the status
informations can also be obtained by reading the UARTDR register.
Table 521.
UART data register summary
Name
Offset
Width(bit) Type Reset value
Description
UARTDR
0x000
16
RW
16‘h0
UART data.
Table 522.
UARTRSR register bit assignments
Bit
Name
Reset value Description
[07:04]
Reserved
-
Read: undefined. Write: should be zero.
[03]
OE
1’h0
Overrun error.
See UARTDR register
(
).
[02]
BE
1’h0
Break error.
[01]
PE
1’h0
Parity error.
[00]
FE
1’h0
Framing error.
Table 523.
UARTECR register bit assignments
Bit
Name
Reset value Description
[07:00]
-
8’h0
Clear errors.