at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 518

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

Figure 33-8. Asynchronous Start Detection
Figure 33-9. Asynchronous Character Reception
33.6.3.3
6249D–ATARM–20-Dec-07
Synchronous Receiver
Clock (x16)
Baud Rate
Sampling
Sampling
Sampling
Baud Rate
Example: 8-bit, Parity Enabled
Detection
Clock
RXD
RXD
Start
Clock
RXD
transmitter can occur. Moreover, as soon as the stop bit is sampled, the receiver starts looking
for a new start bit so that resynchronization can also be accomplished when the transmitter is
operating with one stop bit.
Figure 33-8
operates in asynchronous mode.
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. All data bits, the parity
bit and the stop bits are sampled and the receiver waits for the next start bit. Synchronous mode
operations provide a high speed transfer capability.
Configuration fields and bits are the same as in asynchronous mode.
Figure 33-10
1
1
2
2
samples
3
3
16
4
4
and
illustrates a character reception in synchronous mode.
D0
5
5
samples
16
Figure 33-9
6
6
D1
Detection
7
7
Rejection
samples
Start
Start
16
8
0
D2
1
1
samples
illustrate start detection and character reception when USART
16
2
2
3
3
D3
samples
4
4
16
5
D4
samples
6
16
AT91SAM9263 Preliminary
7
D5
samples
8
16
9 10 11 12 13 14 15 16
D6
samples
16
D7
samples
16
Parity
Bit
samples
16
Stop
Bit
Sampling
D0
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