INFRARED INTERFACE
The infrared interface provides
wireless communications port using infrared as
transmission medium. Two IR
implementations have been provided for the
second UART in this chip (logical device 5),
IrDA and Amplitude Shift Keyed IR. The IR
transmission can use the standard UART2 TX
and RX pins or optional IRTX2 and IRRX2 pins.
These can be selected through the configuration
registers.
a
two-way
serial bit time. A “1” is signaled by sending no
transmission the bit time. Please refer to the
AC timing for the parameters of the ASK-IR
waveform.
a
If the Half Duplex option is chosen, there is a
time-out when the direction of the transmission
is changed. This time-out starts at the last bit
transferred during a transmission and blocks the
receiver input until the timeout expires. If the
transmit buffer is loaded with more data before
the time-out expires, the timer is restarted after
the new byte is transmitted. If data is loaded
into the transmit buffer while a character is
being received, the transmission will not start
until the time-out expires after the last receive
bit has been received. If the start bit of another
character is received during this time-out, the
timer is restarted after the new character is
received. The IR half duplex time-out is
programmable via CRF2 in Logical Device 5.
This register allows the time-out to be
programmed to any value between 0 and
10msec in 100msec increments.
IrDA allows serial communication at baud rates
up to 115K Baud. Each word is sent serially
beginning with a “0” value start bit. A “0” is
signaled by sending a single IR pulse at the
beginning of the serial bit time. A “1” is signaled
by sending no IR pulse during the bit time.
Please refer to the AC timing for the parameters
of these pulses and the IrDA waveform.
The Amplitude Shift Keyed IR allows serial
communication at baud rates up to 19.2K Baud.
Each word is sent serially beginning with a “0”
value start bit. A “0” is signaled by sending a
500 kHz
waveform for the duration of the
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