Datasheet

773
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
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 40-24 shows the block diagram of the Receiver Time-out feature.
Figure 40-24. Receiver Time-out Block Diagram
Table 40-10 gives the maximum time-out period for some standard baud rates.
Table 40-10. Maximum Time-out Period
Baud Rate (Bit/s) Bit Time (µs) Time-out (ms)
600 1,667 109,225
1,200 833 54,613
2,400 417 27,306
4,800 208 13,653
9,600 104 6,827
14,400 69 4,551
19,200 52 3,413
28,800 35 2,276
38,400 26 1,704
56,000 18 1,170
57,600 17 1,138
200,000 5 328
16-bit Time-out
Counter
0
TO
TIMEOUT
Baud Rate
Clock
=
Character
Received
RETTO
Load
Clock
16-bit
Value
STTTO
DQ
1
Clear