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Intel
®
IXP42X product line and IXC1100 control plane processors—Universal Asynchronous
Receiver Transceiver (UART)
Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
DM September 2006
370 Order Number: 252480-006US
§ §
2XMODE
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, but the transmit encoder generates pulses that are
1.6 µs wide (which is three clock periods at the frequency of 1.8432 MHz) —
rather than the normal pulses of 3/16th of a bit time wide.
The shorter infrared pulse generated with XMODE set to 1, reduces the 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
th
of a bit time wide
1 = Transmit pulse with is 1.6 µs
1 RCVEIR
Receiver SIR Enable: When the RCVEIR bit is set to logic 1, the IRDA decoder
processes the signal from the rxd pin. If RCVEIR is cleared, then all clocking to
the IRDA decoder is blocked and the device’s rxd pin is fed directly to the UART.
0 = Receiver input is in normal UART mode
1 = Receiver input is in infrared mode
0XMITIR
Transmitter SIR Enable: When the XMITIR bit is set to logic 1, the IRDA
encoder processes the normal txd output from the UART before it is fed to the
device pin. If XMITIR is cleared, all clocking to the IRDA encoder is blocked and
the UART’s txd signal is connected directly to the device pin.
0 = Transmit output is in normal UART mode
1 = Transmit output is in infrared mode
Register
ISR (Sheet 2 of 2)
Bits Name Description