LSI Logic Confidential
SIO Register Descriptions
15-81
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
OUT) from the baud rate generator that is 16 times the
desired baud rate.
Refer to
Section 15.4.2, “Baud Rate Generator,” page 15-
for more information on generating a desired baud
rate from a given system clock.
UART1 / UART2 Transmit Holding Register (THR)
Offset = 0xBE0100 / 0xBE0180
Write only
Default = 0x0000 0000
TDATA
Transmit Data
31:24
The host processor writes into this register the data byte
to be transmitted. In FIFO mode, data bytes to be trans-
mitted are written into the transmit FIFO, which can hold
16 bytes. Depending upon the mode, the data byte from
the Transmit Holding Register or from the transmit FIFO
is transferred to the Transmit Shift Register at an appro-
priate time, and is transmitted on the SOUT pin.
After module reset, the Transmit Holding Register is
empty, so the THRE bit in the Line Status Register is set.
This causes an interrupt to the SPARC processor if the
interrupts of the UART are enabled. The SPARC proces-
sor can reset this interrupt by either loading data into the
Transmit Holding Register, or by reading the Interrupt
Identification Register. In the second case, the interrupt
is reset only if the highest priority interrupt awaiting ser-
vice in the UART is the THRE interrupt. Once reset, the
THRE bit is set again only when the SPARC processor
loads data into the Transmit Holding Register, and then
the data is transferred to the Transmit Shift Register. In
FIFO mode, the THRE bit is reset when the data is
loaded into the transmit FIFO; once reset, it will be set
only after the transmit FIFO is empty.
31
24
23
16
TDATA
RSVD
15
0
RSVD
Содержание DMN-8600
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