Datasheet

441
32142D–06/2013
ATUC64/128/256L3/4U
The number of data bits, endianess, parity mode, and stop bits are selected by the same bits
and fields as for the transmitter (MR.CHRL, MODE9, MSBF, PAR, and NBSTOP). The synchro-
nization mechanism will only consider one stop bit, regardless of the used protocol, and when
the first stop bit has been sampled, the receiver will automatically begin looking for a new start
bit, enabling resynchronization even if there is a protocol miss-match. Figure 20-6 and Figure
20-7 illustrate start bit detection and character reception in asynchronous mode.
Figure 20-6. Asynchronous Start Bit Detection
Figure 20-7. Asynchronous Character Reception
20.6.3.3 Synchronous Receiver
In synchronous mode (SYNC=1), the receiver samples the RXD signal on each rising edge of
the Baud Rate Clock. If a low level is detected, it is considered as a start bit. Configuration bits
and fields are the same as in asynchronous mode.
Sampling
Clock (x16)
RXD
Start
Detection
Sampling
Baud Rate
Clock
RXD
Start
Rejection
Sampling
12345678
123456701234
123456789 10111213141516
D0
Sampling
D0
D1
D2
D3
D4
D5 D6 D7
RXD
Parity
Bit
Stop
Bit
Example: 8-bit, Parity Enabled
Baud Rate
Clock
Start
Detection
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples