Intel IXP45X Developer's Manual page 775

Universal Asynchronous Receiver-Transmitter (UART)—Intel
Product Line of Network Processors
Bits
2
1
0
August 2006
Order Number: 306262-004US
Register
Name
Transmit Pulse Width Select: When XMODE is set to 0, clocking of the IRDA
transmit and receive logic is done by the UART clock, which must be operating
in the 16X mode. When XMODE is set to a 1, the operation of the receive
decoder does not change. The transmit encoder, however, generates pulses
1.6 µs wide (which is three clock periods at frequency 1.8432 MHz) — instead of
the normal 3/16th of a bit time wide.
The shorter infrared pulse — generated with XMODE set to 1 — reduces the
XMODE
power consumed by the LEDs. At 2,400 bps, the LED would normally be
activated for 78 µs for each 0 bit transmitted. With XMODE set, the LED would
be activated for only 1.6 µs.
This would reduce the power consumed by the LED by a factor of almost 48.
0 = Transmit pulse width is 3/16
1 = Transmit pulse with is 1.6us
(Reserved)
(Reserved)
Intel
® ®
IXP45X and Intel IXP46X
ISR
(Sheet 2 of 2)
Description
th
of a bit time wide
® ®
IXP45X and Intel IXP46X Product Line of Network Processors
Developer's Manual
775