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CC3200: RSSI sudden drop

Prodigy 110 points

Replies: 5

Views: 49

Part Number: CC3200

Greetings,

I am working on a CC3200 MCU and I am facing a problem which origins remain unclear. My device's RSSi is usually between -58 and -36, but sometimes and for no apparent reason it suddenly drops to -99 then goes back up in less than a second.

Could you please tell me more about the possible reasons for this problem?

My most sincere thanks in advance.

  • Guru 36675 points

    Hi,

    What exact code do you use for get RSSI? How often do you call this code? How much data do you transmit between to calls of code?

    Jan


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  • In reply to Hnz:

    Hello Mr. Jan,

    Thank you for your fast answer.

    As indicated in "CC3100/CC3200 SimpleLink Wi-Fi Internet-on-a-Chip User's Guide (Rev. B)", section 17, I created a variable of type SlGetRxStatResponse_t and then I returned the output of sl_WlanRxStatGet() in this variable as shown below:

    SlGetRxStatResponse_t rssiRxStat;
    int32_t i32RssiValue;
    int16_t i16RetValue;
    
    i32RssiValue = -99;
    i16RetValue = sl_WlanRxStatGet(&rssiRxStat, 0);

    This code is called periodically ( the period must be superior than one second in all cases ). The amount of data transmitted is 33kb/s, but in our case it was about 15kb/s.  
    
    

    Best Regards,



  • Guru 36675 points

    In reply to Wajdi Belghouthi:

    Hi,

    I think this is not all your code about reading RSSI. I suppose that you are using this my code form my previous answer to you.

    At that code is -99 returned in case of error code from sl_WlanRxStatGet(). -99 is not a real RSSI value. It is only value which indicates error.

    Reading RSSI values in 1sec interval is unnecessary fast and may to result less stable values. RSSI is calculated from an incoming packets and at that case you will have not enough incoming packets for reasonable results.

    Jan


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  • In reply to Hnz:

    Hello Mr. Jan,

    Yes in fact I am using a piece of code that resembles the one presented above, I just didn't know how much code I was allowed to present on the forum.

    What's the minimal amount of time with which I can get completely stable LQI?

    Best Regards,

    Wajdi.

  • Guru 38495 points

    In reply to Wajdi Belghouthi:

    Hi Wajdi,

    This depends on how many packets comes via WLAN interface. But for a data rate stated above I think reasonable time could be between 5 to 10sec.

    Jan


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