SX1210 SEMTECH [Semtech Corporation], SX1210 Datasheet - Page 43

• Manufacturer Part Number: SX1210
• Description: Ultra-Low Power Integrated UHF Receiver
• Manufacturer: SEMTECH [Semtech Corporation]

In Rx mode the packet handler extracts the user payload to the FIFO by performing the following operations:
Only the payload (including optional address and length fields) is made available in the FIFO.
Payload_ready and CRC_OK interrupts (the latter only if CRC is enabled) can be generated to indicate the end of
the packet reception.
By default, if the CRC check is enabled and fails for the current packet, then the FIFO is automatically cleared and
neither of the two interrupts are generated and new packet reception is started. This autoclear function can be
disabled via PKTParam_CRC_autoclr bit and, in this case, even if CRC fails, the FIFO is not cleared and only
Payload_ready IRQ source is asserted.
Once
PKTParam_Fifo_stby_access. At the end of the reception, although the FIFO automatically stops being filled, it is
still up to the user to explicitly exit Rx mode if required. (e.g. go to Stby to get payload). FIFO must be empty for a
new packet reception to start.
SX1210’s packet handler offers several mechanisms for packet filtering ensuring that only useful packets are made
available to the uC, reducing significantly system power consumption and software complexity.
Sync word filtering/recognition is automatically enabled in Packet mode. It is used for identifying the start of the
payload and also for network identification. As previously described, the Sync word recognition block is configured
(size, error tolerance, value) via RXParam_Sync_size, RXParam_Sync_tol and SYNCParam configuration
registers. This information is used to filter packets in Rx.
Every received packet which does not start with this locally configured Sync word is automatically discarded and no
interrupt is generated.
Rev 2– Sept 8
ADVANCED COMMU
Receiving the preamble and stripping it off.
Detecting the Sync word and stripping it off.
Optional DC-free decoding of data.
Optionally checking the address byte.
Optionally checking CRC and reflecting the result on CRC_status bit and CRC_OK IRQ source.
fully
5.5.3. Rx Processing
5.5.4. Packet Filtering
th
, 2008
received,
5.5.4.1. Sync Word Based
NICATIONS & SENSING
1 to 4 bytes
the
Preamble
Optional User provided fields which are part of the payload
Message part of the payload
Fields processed and removed by the packet handler
payload
1 to 4 bytes
Figure 35: Variable Length Packet Format
Sync Word
can
Length
also
byte
Page 43 of 73
Optional DC free data decoding
CRC checksum calculation
be
Address
byte
Payload/FIFO
fully
0 to (FIFO size - 1) bytes
or
Message
partially
retrieved
2-bytes
CRC
in
Stby
www.semtech.com
SX1210
mode
via