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2016-04-28 - Giant Gecko Family - d0053_Rev1.20
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Table 17.10. USART IrDA Pulse Widths
IRPW
Pulse width OVS=0
Pulse width OVS=1
Pulse width OVS=2
Pulse width OVS=3
00
1/16
1/8
1/6
1/4
01
2/16
2/8
2/6
N/A
10
3/16
3/8
N/A
N/A
11
4/16
N/A
N/A
N/A
By default, no filter is enabled in the IrDA demodulator. A filter can be enabled by setting IRFILT in
USARTn_IRCTRL. When the filter is enabled, an incoming pulse has to last for 4 consecutive clock
cycles to be detected by the IrDA demodulator.
Note that by default, the idle value of the USART data signal is high. This means that the IrDA modulator
generates negative pulses, and the IrDA demodulator expects negative pulses. To make the IrDA module
use RZI signalling, both TXINV and RXINV in USARTn_CTRL must be set.
The IrDA module can also modulate a signal from the PRS system, and transmit a modulated signal to
the PRS system. To use a PRS channel as transmitter source instead of the USART, set IRPRSEN in
USARTn_IRCTRL high. The channel is selected by configuring IRPRSSEL in USARTn_IRCTRL.
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