SAM3X8C Atmel Corporation, SAM3X8C Datasheet - Page 793

• Manufacturer Part Number: SAM3X8C
• Manufacturer: Atmel Corporation

35.7.3.5
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
Radio Interface: Manchester Encoded USART Application
Figure 35-15. Preamble Pattern Mismatch
Figure 35-16. Manchester Error Flag
When the start frame delimiter is a sync pattern (ONEBIT field to 0), both command and data
delimiter are supported. If a valid sync is detected, the received character is written as RXCHR
field in the US_RHR register and the RXSYNH is updated. RXCHR is set to 1 when the received
character is a command, and it is set to 0 if the received character is a data. This mechanism
alleviates and simplifies the direct memory access as the character contains its own sync field in
the same register.
As the decoder is setup to be used in unipolar mode, the first bit of the frame has to be a zero-to-
one transition.
This section describes low data rate RF transmission systems and their integration with a Man-
chester encoded USART. These systems are based on transmitter and receiver ICs that support
ASK and FSK modulation schemes.
The goal is to perform full duplex radio transmission of characters using two different frequency
carriers. See the configuration in
Manchester
encoded
Manchester
data
encoded
data
sampling points
Txd
Txd
Manchester coding error
Preamble Length
Preamble Mismatch
Figure
is set to 4
Preamble Length is set to 8
35-17.
and Start Frame Delimiter
Preamble subpacket
were successfully
SFD
Preamble Mismatch
decoded
invalid pattern
Entering USART character area
Elementary character bit time
SFD
SAM3X/A
SAM3X/A
Coding Error
Manchester
detected
DATA
793
793