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How to read RSSI in CC2430?

Andy Lo
Prodigy 80 points

Other Parts Discussed in Thread: CC2430, CC2520

Now I have a ZigBee system--CC2430, including tracking tags(reader), blind tags and receivers.

For every blind tags, I want to read the received signal strength indicator(RSSI) in CC2430 module, and transport to my pc via rs232.

Can I do that in the CC2430 module? If can, what should I do?

  • 0
    TI__Expert 3140 points

    I'm not sure about the RSSI value, but the LQI (Link Quality Index) is a part of every received message. All you have to do is parse the LQI out of the received data structure ...

     

    typedef struct
    {
      osal_event_hdr_t hdr;
      uint16 groupId;
      uint16 clusterId;
      afAddrType_t srcAddr;
      byte endPoint;
      byte wasBroadcast;
      byte LinkQuality;
      byte SecurityUse;
      uint32 timestamp;
      afMSGCommandFormat_t cmd;
    } afIncomingMSGPacket_t;
  • 0 in reply to Notsane
    Expert 1835 points

    Hi Notsane,

    I would like to ask you if the value that we can see in the Ti Packet Sniffer for the frames which are analyzed

    are the same that we can see in an AfIncomingMSG messag in API Texas?

    Because, I see for exemple my frames which have a good LQI on Packet Sniffer (255 for exemple) and

    a less good in AfIncomingMSG (120 for the same frame). Does one look for RSSI and the other for LQI?

    Thanks,

    Launix.

  • 0 in reply to launix
    TI__Expert 3140 points

    The LQI that you're seeing on the Packet Sniffer display has been inserted into the packet by the receiving device ... which is the sniffer hardware. It probably has a really nice whip antenna with a near circular radiation pattern. When you are looking at the LQI in the received data structure, it has been inserted by the device that you're debugging. That's probably a board with a dipole or F board antenna with a distinct bow-tie radiation pattern. So it's very likely the the LQIs will differ, given the different placement, orientation, antenna pattern, etc ...

    Scott

     

  • 0 in reply to Notsane
    Expert 1835 points

    In fact, I compare the Packet Sniffer with a SmartRF05EB and my own board with a CC2520 + ceramic antenna on the board.

    I try to make the test with the twice boards very near. So, you mean that the two values are get from the twice AfIncomingMSG_LQI_Value?

    Does it means that my board are not so good than the SmartRF for RF sensitivity?

    Thanks, Launix.

  • 0 in reply to launix
    TI__Expert 3140 points

    I don't quite understand what it is that you're asking.

    Ceramic antennas are relatively poor performers compared to a whip or a good PC board antenna, all things considered. Don't expect that one antenna is as good as any other, they're not. Antenna design is a fine art and people make their living doing only that.

    Ceramic antennas do fit in a much smaller space, though. It's all a trade-off.

    Scott