at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 531

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

33.6.5.3
Figure 33-25. IrDA Demodulator Operations
6249D–ATARM–20-Dec-07
Receiver
Counter
Value
Input
MCK
RXD
IrDA Demodulator
6
Rejected
5
Pulse
4
Table 33-10. IrDA Baud Rate Error (Continued)
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 33-25
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.
Peripheral Clock
32 768 000
40 000 000
3 686 400
20 000 000
32 768 000
40 000 000
3 686 400
20 000 000
32 768 000
40 000 000
3 686 400
20 000 000
32 768 000
3
2
6
illustrates the operations of the IrDA demodulator.
6
5
Baud Rate
4
Accepted
38 400
38 400
19 200
19 200
19 200
19 200
Pulse
9 600
9 600
9 600
9 600
2 400
2 400
2 400
3
2
1
0
AT91SAM9263 Preliminary
107
130
130
213
260
521
853
CD
53
65
12
65
24
96
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
19.53
19.53
19.53
19.53
78.13
78.13
78.13
4.88
4.88
9.77
9.77
9.77
9.77
531