IRCC2.0 SMSC Corporation, IRCC2.0 Datasheet - Page 62

• Manufacturer Part Number: IRCC2.0
• Description: Infrared Communications Controller
• Manufacturer: SMSC Corporation

When active, the DATA DONE flag (Register
Block Zero, Line Control Register A) alerts the
transmitter that the next FIFO underrun condition
signifies the end of the valid payload data and
that an EOF should begin (Figure 24). During
DMA operations TC automatically sets the DATA
DONE flag.
A counter that is initialized with a value from the
Tx Data Size register or from a Message Byte
Count register when the message begins can
also signal the end of the valid payload data. If
nActive Frame
EOM Interrupt
FIFO Empty
Data Done
Tx Enable
FIGURE 24 - IrDA FIR TX MESSAGE TIMING (SOFTWARE CRC)
nActive Frame
EOM Interrupt
Data Done/TC
FIFO Empty
Tx Enable
FIGURE 25 - TX ABORT ON UNDERRUN TIMING
BOF
BOF
A
A
62
C
the counter goes to zero before the FIFO is
empty the SCE will behave as if a FIFO underrun
with an active DATA DONE flag had occurred
(not shown).
The DATA DONE flag is cleared following the
EOM, regardless of how the bit was set. If the
DATA DONE flag is inactive when an underrun
occurs, the transmitter aborts the message and
sets the Abort and Underrun flags appropriately
(Figure 25).
C
I
I
Underrun Error
Abort Error
Abort
FCS
EOF