AT91CAP7E Datasheet, PDF (373/520 Pages) ATMEL Corporation – Customizable Microcontroller

AT91CAP7E
Table 29-10. IrDA Baud Rate Error (Continued)
Peripheral Clock
Baud Rate
CD
32 768 000
38 400
53
40 000 000
38 400
65
3 686 400
19 200
12
20 000 000
19 200
65
32 768 000
19 200
107
40 000 000
19 200
130
3 686 400
9 600
24
20 000 000
9 600
130
32 768 000
9 600
213
40 000 000
9 600
260
3 686 400
2 400
96
20 000 000
2 400
521
32 768 000
2 400
853
Baud Rate Error
0.63%
0.16%
0.00%
0.16%
0.31%
0.16%
0.00%
0.16%
0.16%
0.16%
0.00%
0.03%
0.04%
Pulse Time
4.88
4.88
9.77
9.77
9.77
9.77
19.53
19.53
19.53
19.53
78.13
78.13
78.13
29.6.5.3
IrDA Demodulator
The demodulator is based on the IrDA Receive filter comprised of an 8-bit down counter which is
loaded with the value programmed in US_IF. When a falling edge is detected on the RXD pin,
the Filter Counter starts counting down at the Master Clock (MCK) speed. If a rising edge is
detected on the RXD pin, the counter stops and is reloaded with US_IF. If no rising edge is
detected when the counter reaches 0, the input of the receiver is driven low during one bit time.
Figure 29-35 illustrates the operations of the IrDA demodulator.
Figure 29-35. IrDA Demodulator Operations
MCK
RXD
Counter
Value
Receiver
Input
65432 6
Pulse
Rejected
6543210
Pulse
Accepted
As the IrDA mode uses the same logic as the ISO7816, note that the FI_DI_RATIO field in
US_FIDI must be set to a value higher than 0 in order to assure IrDA communications operate
correctly.
8549A–CAP–10/08
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