Atmel Evaluation Kit for AT32uC3A0512, 32-Bit AVR Microcontroller Atmel ATEVK1105 ATEVK1105 Data Sheet
Product codes
ATEVK1105
313
AT32UC3A
Figure 26-10.
Start Frame Delimiter
26.7.3.3
Drift Compensation
Drift compensation is available only in 16X oversampling mode. An hardware recovery system
allows a larger clock drift. To enable the hardware system, the bit in the MAN register must be
set. If the RXD edge is one 16X clock cycle from the expected edge, this is considered as nor-
mal jitter and no corrective actions is taken. If the RXD event is between 4 and 2 clock cycles
before the expected edge, then the current period is shortened by one clock cycle. If the RXD
event is between 2 and 3 clock cycles after the expected edge, then the current period is length-
ened by one clock cycle. These intervals are considered to be drift and so corrective actions are
automatically taken.
Figure 26-11.
Bit Resynchronization
26.7.3.4
Asynchronous Receiver
If the USART is programmed in asynchronous operating mode (SYNC = 0), the receiver over-
samples the RXD input line. The oversampling is either 16 or 8 times the Baud Rate clock,
depending on the OVER bit in the Mode Register (MR).
Manchester
encoded
data
Txd
SFD
DATA
One bit start frame delimiter
Preamble Length
is set to 0
Manchester
encoded
data
Txd
SFD
DATA
Command Sync
start frame delimiter
Manchester
encoded
data
Txd
SFD
DATA
Data Sync
start frame delimiter
RXD
Oversampling
16x Clock
Sampling
point
Expected edge
Tolerance
Synchro.
Jump
Sync
Jump
Synchro.
Error
Synchro.
Error
32058K
AVR32-01/12