SAM4L Datasheet, PDF (591/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
Table 24-13. IrDA Baud Rate Error (Continued)
Peripheral Clock
Baud Rate
CD
3 686 400
38 400
6
20 000 000
38 400
33
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
0.00%
1.38%
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
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
24.6.9.3
IrDA Demodulator
The demodulator depends on an 8-bit down counter loaded with the value in the IRDA_Filter
field in the IrDA Filter Register (IFR.IRDA_FILTER). When a falling edge on RXD is detected,
the counter starts decrementing at CLK_USART speed. If a rising edge on RXD is detected , the
counter stops and is reloaded with the IrD Filter value. If no rising edge has been detected when
the counter reaches zero, the receiver input is pulled low during one bit period, see Figure 24-
26. Writing a one to the Infrared Receive Line Filter bit (MR.FILTER), enables a noise filter that,
instead of using just one sample, will choose the majority value from three consecutive samples.
Figure 24-26. IrDA Demodulator Operations
CLK_USART
RXD
Counter
Value
Receiver
Input
6 5432 6
Pulse
Rejected
Pulse
6 5 4 3 2 1 0 _Accepted
Driven Low During 16 Baud Rate Clock Cycles
24.6.10 LIN Mode
The USART features a Local Interconnect Network (LIN) 1.3 and 2.0 compliant mode, embed-
ding full error checking and reporting, automatic frame processing with up to 256 data bytes,
customizable response data lengths, and requiring minimal CPU resources. The LIN mode is
enabled by writing 0xA (master) or 0xB (slave) to MR.MODE.
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