Datasheet

Figure 34-6. USART Rx Error Calculation Example
+
+
Error Max 3.3%
Error Min -4.35%
Baud Rate 2Mbps
SERCOM Receiver error acceptance
sampling = x16
data bits = 10
parity = 0
start bit = stop bit = 1
No baud generator offset error
Fbaud(2Mbps) = 32MHz *1(BAUD=0) /16
+
Recommended
max. Rx Error +/-1.5%
(example)
Error Max 3.3%
Error Min -4.35%
Error Max 3.0%
Error Min -4.05%
Transmitter Error*
Accepted
Receiver Error
security margin
*Transmitter Error depends on the external transmitter used in the application.
It is advised that it is within the Recommended max. Rx Error (+/-1.5% in this example).
Larger Transmitter Errors are acceptable but must lie within the Accepted Receiver Error.
Related Links
33.6.2.3 Clock Generation – Baud-Rate Generator
33.6.2.3.1 Asynchronous Arithmetic Mode BAUD Value Selection
34.6.3 Additional Features
34.6.3.1 Parity
Even or odd parity can be selected for error checking by writing 0x1 to the Frame Format bit field in the
Control A register (CTRLA.FORM).
If even parity is selected (CTRLB.PMODE=0), the Parity bit of an outgoing frame is '1' if the data contains
an odd number of bits that are '1', making the total number of '1' even.
If odd parity is selected (CTRLB.PMODE=1), the Parity bit of an outgoing frame is '1' if the data contains
an even number of bits that are '0', making the total number of '1' odd.
When parity checking is enabled, the parity checker calculates the parity of the data bits in incoming
frames and compares the result with the Parity bit of the corresponding frame. If a parity error is detected,
the Parity Error bit in the Status register (STATUS.PERR) is set.
34.6.3.2 Hardware Handshaking
The USART features an out-of-band hardware handshaking flow control mechanism, implemented by
connecting the RTS and CTS pins with the remote device, as shown in the figure below.
Figure 34-7. Connection with a Remote Device for Hardware Handshaking
RXD
CTS
RTS
USART
TXD
RTS
CTS
Remote
Device
TXD
RXD
Hardware handshaking is only available in the following configuration:
• USART with internal clock (CTRLA.MODE=1),
• Asynchronous mode (CTRLA.CMODE=0), and
• Flow control pinout (CTRLA.TXPO=2).
SAM D5x/E5x Family Data Sheet
SERCOM USART - SERCOM Synchronous and Asyn...
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 931