INFRARED INTERFACE
The FDC37C669's infrared interface provides
a two-way wireless communications port using
infrared as transmission medium. Two
infrared implementations have been provided in
the FDC37C669, IrDA and Amplitude Shift
Keyed IR.
bit time. A one is signaled by sending no
transmission the bit time. Please refer to the
AC timing for the parameters of the ASKIR
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 time-out 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 time-out is four character times.
A character time is defined as 10 bit times
regardless of the actual word length being used.
IrDA allows serial communication at baud rates
up to 115K Baud. Each word is sent serially
beginning with a zero value start bit. A zero is
signaled by sending a single infrared pulse at
the beginning of the serial bit time. A one is
signaled by sending no infrared 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 infrared allows serial
communication at baud rates up to 19.2K Baud.
Each word is sent serially beginning with a zero
value start bit. A zero is signaled by sending a
500kHz waveform for the duration of the serial
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