SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 799

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
If STTTO is performed, the counter clock is stopped until a first character is received. The idle
state on RXD before the start of the frame does not provide a time-out. This prevents having to
obtain a periodic interrupt and enables a wait of the end of frame when the idle state on RXD is
detected.
If RETTO is performed, the counter starts counting down immediately from the value TO. This
enables generation of a periodic interrupt so that a user time-out can be handled, for example
when no key is pressed on a keyboard.
Figure 35-24
Figure 35-24. Receiver Time-out Block Diagram
Table 35-11
Table 35-11. Maximum Time-out Period
• Stop the counter clock until a new character is received. This is performed by writing the
• Obtain an interrupt while no character is received. This is performed by writing US_CR with
RETTO
Control Register (US_CR) with the STTTO (Start Time-out) bit to 1. In this case, the idle state
on RXD before a new character is received will not provide a time-out. This prevents having
to handle an interrupt before a character is received and allows waiting for the next idle state
on RXD after a frame is received.
the RETTO (Reload and Start Time-out) bit to 1. If RETTO is performed, the counter starts
counting down immediately from the value TO. This enables generation of a periodic interrupt
so that a user time-out can be handled, for example when no key is pressed on a keyboard.
Character
Received
Baud Rate
STTTO
gives the maximum time-out period for some standard baud rates.
bit/sec
14400
19200
28800
33400
1 200
2 400
4 800
9 600
shows the block diagram of the Receiver Time-out feature.
600
1
D
Clear
Q
Baud Rate
Clock
Clock
Bit Time
1 667
833
417
208
104
μs
69
52
35
30
16-bit Time-out
Counter
TO
Load
16-bit
Value
0
Time-out
109 225
54 613
27 306
13 653
6 827
4 551
3 413
2 276
1 962
ms
SAM3X/A
SAM3X/A
=
TIMEOUT
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