at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 523

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

Figure 33-14. Receiver Time-out Block Diagram
6249D–ATARM–20-Dec-07
RETTO
Character
Received
STTTO
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 33-14
Table 33-8
Table 33-8.
• Obtain an interrupt while no character is received. This is performed by writing US_CR with
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 at 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.
1
D
Baud Rate
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.
Clear
600
Q
Baud Rate
Maximum Time-out Period
Clock
Clock
16-bit Time-out
Counter
TO
Bit Time
1 667
AT91SAM9263 Preliminary
Load
833
417
208
104
µs
69
52
35
30
16-bit
Value
0
=
TIMEOUT
Time-out
109 225
54 613
27 306
13 653
6 827
4 551
3 413
2 276
1 962
ms
523