Datasheet

715
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
 Configure the TXD pin as PIO and set it as an output to 0 (to avoid LED emission). Disable the internal pull-up
(better for power consumption).
 Receive data
35.7.5.1 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 35-12.
Figure 35-34 shows an example of character transmission.
Figure 35-34.IrDA Modulation
35.7.5.2 IrDA Baud Rate
Table 35-13 gives some examples of CD values, baud rate error and pulse duration. Note that the requirement on the
maximum acceptable error of ±1.87% must be met.
Table 35-12. IrDA Pulse Duration
Baud Rate Pulse Duration (3/16)
2.4 Kb/s 78.13 μs
9.6 Kb/s 19.53 μs
19.2 Kb/s 9.77 μs
38.4 Kb/s 4.88 μs
57.6 Kb/s 3.26 μs
115.2 Kb/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 35-13. 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
3 686 400 38 400 6 0.00% 4.88