Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet

SAM4E [DATASHEET]

Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14

900

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 Manchester 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

data

Txd

SFD

Preamble Length 

is set to 4

Elementary character bit time

Manchester

Coding Error

detected

sampling points

Preamble subpacket

and Start Frame Delimiter

were successfully

decoded

Entering USART character area

LNA

VCO

RF filter

Demod

control

bi-dir

line

PA

RF filter

Mod

VCO

control

Manchester

decoder

Manchester

encoder

USART

Receiver

USART

Emitter

ASK/FSK 

Upstream Receiver

ASK/FSK

downstream transmitter

Upstream

Emitter

Downstream

Receiver

Serial

Configuration

Interface

Fup frequency Carrier

Fdown frequency Carrier