Datasheet

595
42023E–SAM–07/2013
ATSAM4L8/L4/L2
24.6.9.1 IrDA Modulation
The RZI modulation scheme is used, where a zero is represented by a light pulse 3/16 of a bit
period, and no pulse to represent a one. Some examples of signal pulse duration are shown in
Table 24-12.
Figure 24-26 shows an example of character transmission.
Figure 24-26. IrDA Modulation
24.6.9.2 IrDA Baud Rate
As the IrDA mode shares some logic with the ISO7816 mode, the FIDI.FI_DI_RATIO field must
be configured correctly. See Section “24.6.16” on page 611. Table 24-13 shows some examples
of BRGR.CD values, baud rate error, and pulse duration. Note that the maximal acceptable error
rate of ±1.87% must be met.
Table 24-12. IrDA Pulse Duration
Baud Rate Pulse Duration (3/16)
2.4 Kbit/s 78.13 µs
9.6 Kbit/s 19.53 µs
19.2 Kbit/s 9.77 µs
38.4 Kbit/s 4.88 µs
57.6 Kbit/s 3.26 µs
115.2 Kbit/s 1.63 µs
Bit Period
Bit Period
3
16
Start
Bit
Data Bits
Stop
Bit
0
0
0
0
0
1
11
1
1
Transmitter
Output
TXD
Table 24-13. IrDA Baud Rate Error
Peripheral Clock Baud Rate CD Baud Rate Error Pulse Time
3 686 400 115 200 2 0.00% 1.63
20 000 000 115 200 11 1.38% 1.63
32 768 000 115 200 18 1.25% 1.63
40 000 000 115 200 22 1.38% 1.63
3 686 400 57 600 4 0.00% 3.26
20 000 000 57 600 22 1.38% 3.26
32 768 000 57 600 36 1.25% 3.26
40 000 000 57 600 43 0.93% 3.26