SX1210 SEMTECH [Semtech Corporation], SX1210 Datasheet - Page 44

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

When the Sync word is detected, payload reception automatically starts and Sync IRQ source is asserted.
Address filtering can be enabled via the PKTParam_Adrs_filt bits. It adds another level of filtering, above Sync
word, typically useful in a multi-node networks where a network ID is shared between all nodes (Sync word) and
each node has its own ID (address).
Three address based filtering options are available:
Please note that the received address byte, as part of the payload, is not stripped off the packet and is made
available in the FIFO.
In variable length Packet mode, PKTParam_Payload_length must be programmed with the maximum length
permitted. If received length byte is smaller than this maximum then the packet is accepted and processed,
otherwise it is discarded.
Please note that the received length byte, as part of the payload, is not stripped off the packet and is made
available in the FIFO.
To disable this function the user should set the value of the PKTParam_Payload_length to the value of the FIFO
size selected.
The CRC check is enabled by setting bit PKTParam_CRC_on. It is used for checking the integrity of the message.
By default, if the CRC check fails then the FIFO is automatically cleared and no interrupt is generated. This filtering
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 interrupt goes high. Please note that in both cases, the two CRC checksum bytes
are stripped off by the packet handler and only the payload is made available in the FIFO.
The CRC is based on the CCITT polynomial as shown in Figure 36. This implementation also detects errors due to
leading and trailing zeros.
Rev 2– Sept 8
ADVANCED COMMUNICATIONS & SENSING
Adrs_filt = 01: Received address field is compared with internal register Node_Adrs. If they match then the
packet is accepted and processed, otherwise it is discarded.
Adrs_filt = 10: Received address field is compared with internal register Node_Adrs and the constant 0x00. If
either is a match, the received packet is accepted and processed, otherwise it is discarded. This additional
check with a constant is useful for implementing broadcast in a multi-node networks.
Adrs_filt = 11: Received address field is compared with internal register Node_Adrs and the constants 0x00 &
0xFF. If any of the three matches, then the received packet is accepted and processed, otherwise it is
discarded. These additional checks with constants are useful for implementing broadcast commands of all
nodes.
On your Tx side a two byte CRC checksum should be calculated on the payload part of the packet and
appended to the end of the message.
On SX1210 (Rx side) the checksum is calculated on the received payload and compared with the two
checksum bytes received. The result of the comparison is stored in the PKTParam_CRC_status bit and
CRC_OK IRQ source.
th
, 2008
5.5.4.2. Address Based
5.5.4.3. Length Based
5.5.4.4. CRC Based
Page 44 of 73
www.semtech.com
SX1210