SX1213 datasheet(39/65 Pages) SEMTECH

39 / 65 page

SX1213

ADVANCED COMMUNICATIONS & SENSING

Rev.2 – July 1

st, 2009

Page 39 of 65

www.semtech.com

5.4. Buffered Mode

5.4.1. General Description

As illustrated in Figure 30, for Buffered mode operation the NRZ data from the demodulator is not directly accessed

by the uC but stored in the FIFO and accessed via the SPI Data interface. This frees the uC for other tasks

between processing data from the SX1213, furthermore it simplifies software development and reduces uC

performance requirements (speed, reactivity). Note that in this mode the packet handler stays inactive.

An important feature is also the ability to empty the FIFO in Stby mode, ensuring low power consumption and

adding greater software flexibility.

CONTROL

FIFO

(+SR)

DATA

CONFIG

SPI

SYNC

RECOG.

IRQ_0

IRQ_1

MISO

MOSI

SCK

NSS_DATA

NSS_CONFIG

Datapath

SX1213

Data

Figure 30: Buffered Mode Conceptual View

Note that Bit Synchronizer is automatically enabled in Buffered mode. The Sync word recognition must be enabled

(RXParam_Sync_on=1) independently of the FIFO filling method selected (IRQParam_Fifo_fill_method).

5.4.2. Rx Processing

After entering Rx in Buffered mode, the chip requires the uC to retrieve the received data from the FIFO. The FIFO

will actually start being filled with received bytes either; when a Sync word has been detected (in this case only the

bytes following the Sync word are filled into the FIFO) or when the Fifo_fill bit is asserted by the user - depending

on the state of bit, IRQParam_Fifo_fill_method.

In Buffered mode, the packet length is not limited i.e. as long as Fifo_fill is set, the received bytes are shifted into

the FIFO.

The uC software must therefore manage the transfer of the FIFO contents by interrupt and ensure reception of the

correct number of bytes. (In this mode, even if the remote transmitter has stopped, the demodulator will output

random bits from noise)

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