IRCC2.0 SMSC Corporation, IRCC2.0 Datasheet - Page 78

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IRCC2.0

Manufacturer Part Number
IRCC2.0
Description
Infrared Communications Controller
Manufacturer
SMSC Corporation
Datasheet
FIFO Interrupt Interface
Transmit
Transmitting messages with Programmed I/O
using FIFO Interrupt requires writing a fixed
number of data bytes, usually related to the
threshold, whenever the FIFO Interrupt becomes
active.
allows the host to efficiently satisfy the FIFO
service requests until the message transmission
is complete. For slow systems, the FIFO can be
manually filled with transmit data before the
transmitter is enabled.
automatically
An appropriate FIFO Threshold value
FIFO Int. Enable
FIFO Interrupt
EOM Interrupt
String Move
DMA Enable
FIGURE 46 - INTERRUPT DRIVEN PROGRAMMED I/O TRANSMIT TIMING
FIFO Data WRITE
TxServReq
Data Done
Tx Enable
request
DMA Enable
String Move
FIFO FULL
IOW
FIGURE 45 - PROGRAMMED I/O WRITE TIMING
service
IOW
Note: the FIFO will
before
Status READ
the
78
transmitter is activated if the FIFO Threshold is
greater than zero.
Example: Transmit a 256-byte IrDA Message
1.
2.
3.
Set an appropriate FIFO Threshold for the
system type. For the greatest performance
advantage, pre-load the FIFO with transmit
data.
Set the FIFO Interrupt Enable active and
activate the transmitter.
Service the FIFO Interrupts as required. Set
the Data Done flag when all of the transmit
message data has been loaded (Figure 46).

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