Datasheet

444
32142D–06/2013
ATUC64/128/256L3/4U
Table 20-5. Maximum Baud Rate Dependent Timeguard Durations
20.6.3.8 Receiver Time-out
The Time-out Value field in the Receiver Time-out Register (RTOR.TO) enables handling of vari-
able-length frames by detection of selectable idle durations on the RXD line. The value written to
TO is loaded to a decremental counter, and unless it is zero, a time-out will occur when the
amount of inactive bit periods match the initial counter value. If a time-out has not occurred, the
counter will reload and restart every time a new character arrives. A time-out sets the TIMEOUT
bit in CSR. Clearing TIMEOUT can be done in two ways:
• Writing a one to the Start Time-out bit (CR.STTTO). This also aborts count down until the
next character has been received.
• Writing a one to the Reload and Start Time-out bit (CR.RETTO). This also reloads the
counter and restarts count down immediately.
Figure 20-12. Receiver Time-out Block Diagram
Table 20-6. Maximum Time-out Period
Baud Rate (bit/sec) Bit time (µs) Timeguard (ms)
1 200 833 212.50
9 600 104 26.56
14400 69.4 17.71
19200 52.1 13.28
28800 34.7 8.85
33400 29.9 7.63
56000 17.9 4.55
57600 17.4 4.43
115200 8.7 2.21
Baud Rate (bit/sec) 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
16-bit Time-out
Counter
0
TO
TIMEOUT
Baud Rate
Clock
=
Character
Received
RETTO
Load
Clock
16-bit
Value
STTTO
DQ
1
Clear