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SX1231 参数 Datasheet PDF下载

SX1231图片预览
型号: SX1231
PDF下载: 下载PDF文件 查看货源
内容描述: 低功耗集成的UHF收发器 [Low Power Integrated UHF Transceiver]
分类和应用:
文件页数/大小: 78 页 / 889 K
品牌: SEMTECH [ SEMTECH CORPORATION ]
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SX1231  
ADVANCED COMMUNICATIONS & SENSING  
DATASHEET  
5.5.6. Packet Filtering  
SX1231'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.  
5.5.6.1. Sync Word Based  
Sync word filtering/recognition 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) in RegSyncValue  
registers. This information is used, both for appending Sync word in Tx, and filtering packets in Rx.  
Every received packet which does not start with this locally configured Sync word is automatically discarded and no  
interrupt is generated.  
When the Sync word is detected, payload reception automatically starts and SyncAddressMatch is asserted.  
5.5.6.2. Address Based  
Address filtering can be enabled via the AddressFiltering bits. It adds another level of filtering, above Sync word (i.e. Sync  
must match first), 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).  
Two address based filtering options are available:  
Š AddressFiltering = 01: Received address field is compared with internal register NodeAddress. If they match then the  
packet is accepted and processed, otherwise it is discarded.  
Š AddressFiltering = 10: Received address field is compared with internal registers NodeAddress and BroadcastAddress.  
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  
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 addition, NodeAddress and AddressFiltering only apply to Rx. On Tx side, if address filtering is expected, the  
address byte should simply be put into the FIFO like any other byte of the payload.  
As address filtering requires a Sync word match, both features share the same interrupt flag SyncAddressMatch.  
5.5.6.3. Length Based  
In variable length Packet mode, PayloadLength must be programmed with the maximum payload 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 PayloadLength to 255.  
5.5.6.4. CRC Based  
The CRC check is enabled by setting bit CrcOn in RegPacketConfig1. It is used for checking the integrity of the message.  
Rev 2 - Nov 2009  
Page 54  
www.semtech.com  
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