SAM7S256_14 Datasheet, PDF (382/775 Pages) ATMEL Corporation – ARM-based Flash MCU

Figure 31-25. Connection to IrDA Transceivers
USART
Receiver
Demodulator _RXD
Transmitter
Modulator
TXD
IrDA
Transceivers
RX
TX
The receiver and the transmitter must be enabled or disabled according to the direction of the transmission to be
managed.
To receive IrDA signals, the following needs to be done:
• Disable TX and Enable RX
• Configure the TXD pin as PIO and set it as an output at 0 (to avoid LED emission). Disable the internal pull-up
(better for power consumption).
• Receive data
31.6.5.1 IrDA Modulation
For baud rates up to and including 115.2 Kbits/sec, the RZI modulation scheme is used. “0” is represented by a
light pulse of 3/16th of a bit time. Some examples of signal pulse duration are shown in Table 31-9.
Table 31-9.
Baud Rate
2.4 Kb/s
9.6 Kb/s
19.2 Kb/s
38.4 Kb/s
57.6 Kb/s
115.2 Kb/s
IrDA Pulse Duration
Pulse Duration (3/16)
78.13 µs
19.53 µs
9.77 µs
4.88 µs
3.26 µs
1.63 µs
Figure 31-26 shows an example of character transmission.
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
382