IRCC datasheet(57/79 Pages) SMSC

57 / 79 page

Transmit Timing

The SCE IrDA-mode transmitter is enabled by

setting the appropriate SCE MODES bits in SCE

Line Control Register B. If the FIFO Threshold is

zero, message transmission begins as soon as

transmit mode has been enabled and there is

data in the FIFO (Figure 22).

If the FIFO Threshold is greater than zero,

message transmission begins only after transmit

mode has been enabled and the FIFO Threshold

has been exceeded or TC is active (Figure 23).

NOTE: the IrDA-mode SCE transmitter will only

be enabled when the SIR Interaction Pulse

generator is inactive.

Once an IrDA transmission has begun, the End

of Message (EOM) and other state indicators are

cleared and the nActive Frame signal is enabled.

Following the frame check sequence, EOM is

reactivated and an EOM interrupt is generated.

Following the end of the frame, nActive Frame is

disabled (Figure 24).

FIFO E m pty

Tx E n a b le

T r an sm it

A c tive SIP T im e

FIGURE 22 - IrDA FIR TRANSMIT ENABLE TIMING: FIFO THRESHOLD = 0

FIFO T h r e s h old

Tx E n a b le

T r an sm it

Ac tiv e S IP T im e

FIGURE 23 - IrDA FIR TRANSMIT TIMING: FIFO THRESHOLD > 0

IRCC Datasheet(PDF) 57 Page - SMSC Corporation