SAM4L Datasheet, PDF (590/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/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.
Table 24-12. IrDA Pulse Duration
Baud Rate
2.4 Kbit/s
9.6 Kbit/s
19.2 Kbit/s
38.4 Kbit/s
57.6 Kbit/s
115.2 Kbit/s
Pulse Duration (3/16)
78.13 µs
19.53 µs
9.77 µs
4.88 µs
3.26 µs
1.63 µs
Figure 24-25 shows an example of character transmission.
Figure 24-25. IrDA Modulation
Transmitter
Output
Start
Bit
0 10
Data Bits
1 ⁰⁰¹¹
Stop
Bit
01
TXD
24.6.9.2
Bit Period
3
16
Bit
Period
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 606. 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 24-13. 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
42023C–SAM–02/2013
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