martin gonella

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8 years, 4 months ago.

BLE_Observer to get distance estimate?

Hi to everyone! I'm using the BLE_Oberver to detect the presence of iBeacons and it works great but now I need to estimate the distance to my iBeacon. Can I use the TxPower and the RSSI? Or there is another way to do that?

Thank you!

2 Answers

Raviteja Lingineni
8 years, 4 months ago.

Yes. So you can do that by reading the transmit data. The beacon transmits the following: a UUID, Major, Minor and TX Power. The TX power is used for the RSSI.

Read this article: http://www.warski.org/blog/2014/01/how-ibeacons-work/"

It will tell you about the attributes of an ibeacon and how to get distance. I know it answered a lot my questions and what the different parts to the address mean.

Ok great! How do I read the transmit data?

posted by martin gonella 24 Nov 2015

Yes.. so you can print out those values by running through a for loop for the length of advertisingDataLen

so:

Printing Advertising Data

void advertisementCallback(const Gap::AdvertisementCallbackParams_t *params) {
    
 if(params->advertisingDataLen == 30)
 {   
    for (unsigned index = 0; index < params->advertisingDataLen; index++) {

        pc.printf("%02x", params->advertisingData[index]); //print the advertising data by byte
        
    }
    
 }
   pc.printf("\r\n"); //write next transmission on new line

The last byte is the TX data. I used a ibeacon app from the app store that can simulate an ibeacon, and you can change your values and play with the TX data by simulating it.

posted by Raviteja Lingineni 24 Nov 2015
Milan Kipke
7 years, 10 months ago.

Hello,

I used the published example BLE_Observer_Nucleo and tried to print out the advertising data as well as the RSSI- value. However when I ran the programm the RSSI-value as well as the advertising data was empty or zero.

https://developer.mbed.org/users/vcoubard/code/BLE_Observer_Nucleo/

Do you know of any other funktions to read out mayor/minor and the RSSI-Value or do you see any possible mistakes?

Thank you!