SX1212 datasheet(49/77 Pages) SEMTECH

49 / 77 page

SX1212

ADVANCED COMMUNICATIONS & SENSING

Rev 2 – June 18th, 2009

Page 49 of 77

www.semtech.com

5.5. Packet Mode

5.5.1. General Description

Similar to Buffered mode operation, in Packet mode the NRZ data to (from) the (de)modulator is not directly

accessed by the uC but stored in the FIFO and accessed via the SPI Data interface.

In addition, the SX1212’s packet handler performs several packet oriented tasks such as Preamble and Sync word

generation, CRC calculation/check, whitening/dewhitening of data, address filtering, etc. This simplifies still further

software and reduces uC overhead by performing these repetitive tasks within the RF chip itself.

Another important feature is ability to fill and empty the FIFO in Stby mode, ensuring optimum power consumption

and adding more flexibility for the software.

CONTROL

DATA

CONFIG

SPI

PACKET

HANDLER

SYNC

RECOG.

IRQ_0

IRQ_1

MISO

MOSI

SCK

NSS_DATA

NSS_CONFIG

Datapath

SX1212

Data

FIFO

(+SR)

Figure 42: Packet Mode Conceptual View

Note that Bit Synchronizer and Sync word recognition are automatically enabled in Packet mode.

5.5.2. Packet Format

Two types of packet formats are supported: fixed length and variable length, selectable by the

PKTParam_Pkt_format bit. The maximum size of the payload is limited by the size of the FIFO selected (16, 32, 48

or 64 bytes).

5.5.2.1. Fixed Length Packet Format

In applications where the packet length is fixed in advance, this mode of operation may be of interest to minimize

RF overhead (no length byte field is required). All nodes, whether Tx only, Rx only, or Tx/Rx should be

programmed with the same packet length value.

The length of the payload is set by the PKTParam_Payload_length register and is limited by the size of the FIFO

selected.

SX1212 Datasheet(PDF) 49 Page - Semtech Corporation

SX1212 Datasheet(HTML) 49 Page - Semtech Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

Datasheet Download

Link URL