318
8331B–AVR–03/12
Atmel AVR XMEGA AU
24.3 Registers Description
24.3.1 TXPLCTRL – Transmitter Pulse Length Control Register
• Bit 7:0 – TXPLCTRL[7:0]: Transmitter Pulse Length Control
This 8-bit value sets the pulse modulation scheme for the transmitter. Setting this register will
have no effect if IRCOM mode is not selected by a USART.
By leaving this register value to zero, 3/16 of the baud rate period pulse modulation is used.
Setting this value from 1 to 254 will give a fixed pulse length coding. The 8-bit value sets the
number of system clock periods for the pulse. The start of the pulse will be synchronized with the
rising edge of the baud rate clock.
Setting the value to 255 (0xFF) will disable pulse coding, letting the RX and TX signals pass
through the IRCOM module unaltered. This enables other features through the IRCOM module,
such as half-duplex USART, loop-back testing, and USART RX input from an event channel.
TXPCTRL must be configured before the USART transmitter is enabled (TXEN).
24.3.2 RXPLCTRL – Receiver Pulse Length Control Register
• Bit 7:0 – RXPLCTRL[7:0]: Receiver Pulse Length Control
This 8-bit value sets the filter coefficient for the IRCOM transceiver. Setting this register will have
no effect if IRCOM mode is not selected by a USART.
By leaving this register value at zero, filtering is disabled. Setting this value between 1 and 255
will enable filtering, where x+1 equal samples are required for the pulse to be accepted.
RXPCTRL must be configured before the USART receiver is enabled (RXEN).
24.3.3 CTRL – Control Register
• Bit 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
Bit 76543210
+0x01 TXPLCTRL[7:0] TXPLCTRL
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 00000000
Bit 76543210
+0x02 RXPLCTRL[7:0] RXPLCTRL
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
+0x00 – – – – EVSEL[3:0] CTRL
Read/Write R R R R R/W R/W R/W R/W
Initial Value 00000000
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