Artesyn Embedded Technology ATCA-7490, Installation And Use Manual

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Maps and Registers
ATCA-7490 Installation and Use (6806800U11F )
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5.1.4.2.8 Line Status Register (LSR)
This register provides status information to the processor concerning the data transfers. Bits 5
and 6 show information about the transmitter section. The rest of the bits contain information
about the receiver.
In non-FIFO mode, three of the LSR register bits, parity error, framing error, and break
interrupt, show the error status of the character that has just been received. In FIFO mode,
these three bits of status are stored with each received character in the FIFO. LSR shows the
status bits of the character at the top of the FIFO. When the character at the top of the FIFO has
errors, the LSR error bits are set and are not cleared until software reads LSR, even if the
character in the FIFO is read and a new character is now at the top of the FIFO.
Bits one through four are the error conditions that produce a receiver line status interrupt when
any of the corresponding conditions are detected and the interrupt is enabled. These bits are
not cleared by reading the erroneous byte from the FIFO or receive buffer. They are cleared only
by reading LSR. In FIFO mode, the line status interrupt occurs only when the erroneous byte is
at the top of the FIFO. If the erroneous byte being received is not at the top of the FIFO, an
interrupt is generated only after the previous bytes are read and the erroneous byte is moved
to the top of the FIFO.
5 Autoflow control enable (AFE):
1: Autoflow control enabled (auto-# and auto-CTS# or auto-
CTS# only enabled)
0: Autoflow control disabled 0 LPC: r/w
7:6 Reserved 0 LPC: r
Table 5-32 Modem Control Register (MCR) (continued)
LPC IO Address: Base + 4
Bit Description Default Access