AT32UC3C2512C Automotive Atmel Corporation, AT32UC3C2512C Automotive Datasheet - Page 577

• Manufacturer Part Number: AT32UC3C2512C Automotive
• Manufacturer: Atmel Corporation

25.6.3.5
9166C–AVR-08/11
Radio Interface: Manchester Encoded USART Application
Figure 25-14. Preamble Pattern Mismatch
Figure 25-15. Manchester Error Flag
When the start frame delimiter is a sync pattern (ONEBIT field at 0), both command and data
delimiter are supported. If a valid sync is detected, the received character is written as RXCHR
field in the 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
encoded
data
data
sampling points
Txd
Txd
Manchester coding error
Preamble Length
Preamble Mismatch
Figure
is set to 4
Preamble Length is set to 8
25-16.
and Start Frame Delimiter
Preamble subpacket
were successfully
Preamble Mismatch
SFD
decoded
invalid pattern
Entering USART character area
Elementary character bit time
AT32UC3C
SFD
Coding Error
Manchester
detected
DATA
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