LSI Logic Confidential
15-82
Serial I/O Port
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
UART1 / UART2 Receive Buffer Register (RBR)
Offset = 0xBE0100 / 0xBE0180
Read only
Default = 0x0000 0000
RDATA
Receive Data
31:24
The host processor can read received data from this reg-
ister.
In FIFO mode, received data is stored in the receive
FIFO and is made available whenever the SPARC pro-
cessor reads the Receive Buffer Register. The DR (Data
Ready) bit in the Line Status Register monitors the con-
dition of the receive buffer register. When a data byte has
been completely received and transferred to the Receive
Buffer Register from the Receive Shift Register, the DR
bit is set. This can cause an interrupt to the SPARC pro-
cessor if interrupts are enabled.
The DR bit is reset only when the SPARC processor
reads the Receive Buffer Register, or when all the data
from the receive FIFO has been drained (in FIFO mode).
UART1 Interrupt Enable Register / Divisor Latch MSB Register (UART1_IER0_DLM1)
UART2 Interrupt Enable Register / Divisor Latch MSB Register (UART2_IER0_DLM1)
In effect, two registers share the offset address 0x104: UART1_DLM and
UART1_IER. Similarly, two registers share the offset address 0x184:
UART2_DLM and UART2_IER.
The value of the DLAB bit in the UART* Line Control register determines
which register is physically written or read, as shown below:
•
Write UART*_DLM when DLAB = 1
•
Read/Write UART*_IER when DLAB = 0
In either case, these registers are always accessed via the same
software name: UART1_IER0_DLM1 or UART2_IER0_DLM1.
31
24
23
16
RDATA
RSVD
15
0
RSVD
Содержание DMN-8600
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