SM1212E433 Semtech, SM1212E433 Datasheet - Page 49

• Manufacturer Part Number: SM1212E433
• Description: RF Module For SX1212
• Manufacturer: Semtech
• Series: -r
• Type: Transceiver, ISMr

Specifications of SM1212E433

• Frequency: 433MHz
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: SX1212E

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.
Note that Bit Synchronizer and Sync word recognition are automatically enabled in Packet mode.
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).
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.
Rev 2 – June 18th, 2009
ADVANCED COMMUNICATIONS & SENSING
Data
5.5. Packet Mode
Datapath
5.5.1. General Description
5.5.2. Packet Format
Tx
Rx
5.5.2.1. Fixed Length Packet Format
RECOG.
SYNC
HANDLER
PACKET
Figure 42: Packet Mode Conceptual View
SX1212
CONTROL
Page 49 of 77
(+SR)
FIFO
CONFIG
DATA
SPI
www.semtech.com
NSS_CONFIG
MISO
SCK
MOSI
NSS_DATA
IRQ_1
IRQ_0
SX1212