AT32UC3L064_1 ATMEL [ATMEL Corporation], AT32UC3L064_1 Datasheet - Page 389

• Manufacturer Part Number: AT32UC3L064_1
• Description: AVR32 32-bit Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

32099A–AVR32–06/09
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 20-14 on page 389
Figure 20-14. Receiver Time-out Block Diagram
Table 20-9 on page 389
Table 20-9.
• Obtain an interrupt while no character is received. This is performed by writing CR with the
RETTO
handle an interrupt before a character is received and allows waiting for the next idle state on
RXD after a frame is received.
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.
Character
Received
Baud Rate
STTTO
bit/sec
14400
19200
28800
33400
1 200
2 400
4 800
9 600
600
Maximum Time-out Period
1
D
gives the maximum time-out period for some standard baud rates.
shows the block diagram of the Receiver Time-out feature.
Clear
Q
Baud Rate
Clock
Clock
Bit Time
1 667
833
417
208
104
69
52
35
30
µs
16-bit Time-out
Counter
TO
Load
16-bit
Value
0
AT32UC3L
Time-out
109 225
54 613
27 306
13 653
6 827
4 551
3 413
2 276
1 962
=
ms
TIMEOUT
389