cannot talk to dongle after connect

[JimmyD]

I connect to the nRF52840-MDK dongle thru the Serial Terminal (nRF52 Connectivity) it found the comm port and set the baudrate automatically. However, the terminal window constantly fills up the screen with ~/ characters. it repeats every 1 second. What I would like is detailed instructions on how to configure this dongle to be a BT 5 sniffer and read the Extended Advertising for any BT device near the dongle. It would also be helpful to filter the devices seen. Eventually I like to use Python to filter the choices and obtain the advertises data where I can parse the data received. I'm using Windows 10 pro.

Thanks.

[ovrebekk]

Hi James

The nRF Sniffer is documented here. In particular you can refer to the chapter caller nRF Sniffer Usage.

The dongle needs to be programmed with the hex file included in the sniffer download, most likely it has the wrong firmware. This will be described in the documentation I linked to above. 

The sniffer does provide a Python interface, and you can find it documented in the Sniffer API Guide document included in the doc folder of the sniffer download. 

Best regards
Torbjørn

[JimmyD]

Torbjørn,

            The instruction for installation is very hard to follow and leads to a dead end.

First your link takes me to nRF Sniffer usage. The index on the side “Installing the nRF Sniffer starts off as if it is already installed. Very confusing!!

Another is the SnifferAPI.

I cannot find it anywhere.

Since I took too long to try and get this working, I have other priorities, But will circle back to try and get this to work.

Due to my time allocation for this project is short.

Please give me some dummy proof steps to get this working.

 

 

I see a bunch of python code under the nrf_sniffer_for_bluetooth_le_4.1.1 directory I downloaded, but I don’t know which one I need for my application.

 

Greatly appreciate it.

 

James DeLorenzo

[ovrebekk]

Hi again

I played around with this some more, and realized that not all the packets sent by the periodic_adv board was received. It seems my earlier advice about setting findAux=True was necessary after all. 

Fixing this I updated the script to print out all the data, available in the packetList field of the packet. I also print out the name and the flags, and filter on the RSSI and the advertising type to ensure I only print packets for an extended advertiser in close proximity. 

Please find my modified script here:

Fullscreen example_count_by_type_v2.py Download

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import time
from SnifferAPI import Sniffer, UART

nPackets = 0
nPacketsByType = [0,0,0,0,0,0,0,0]
mySniffer = None

def setup():
    global mySniffer
    
    # Find connected sniffers
    ports = UART.find_sniffer()
    
    if len(ports) > 0:
        # Initialize the sniffer on the first COM port found with baudrate 1000000.
        # If you are using an old firmware version <= 2.0.0, simply remove the baudrate parameter here.
        mySniffer = Sniffer.Sniffer(portnum=ports[0], baudrate=1000000)
    
    else:
        print("No sniffers found!")
        return
    
    # Start the sniffer module. This call is mandatory.
    mySniffer.start()
    # Scan for new advertisers
    mySniffer.scan(findAux=True)

    # Wait to allow the sniffer to discover device mySniffer.
    #time.sleep(5)
    # Retrieve list of discovered devicemySniffer.
    #d = mySniffer.getDevices()
    # Find device with name "Example".
    #dev = d.find('Example')
    
    #if dev is not None:
        # Follow (sniff) device "Example". This call sends a REQ_FOLLOW command over UART.
    #    mySniffer.follow(dev)
    #else:
    #    print("Could not find device")

def loop():
    # Enter main loop
    nLoops = 0
    while True:
        time.sleep(0.1)
        # Get (pop) unprocessed BLE packets.
        packets = mySniffer.getPackets()
        
        processPackets(packets) # function defined below
        
        nLoops += 1
        
        # print diagnostics every so often
        if nLoops % 20 == 0:
            #print(mySniffer.getDevices())
            print("inConnection", mySniffer.inConnection)
            print("currentConnectRequest", mySniffer.currentConnectRequest)
            print("packetsInLastConnection", mySniffer.packetsInLastConnection)
            print("nPackets", nPackets)
            print("packet by type", nPacketsByType)
            print()
        
# Takes list of packets
def processPackets(packets):
    for packet in packets:
        # packet is of type Packet
        # packet.blePacket is of type BlePacket
        global nPackets
        if packet.OK:
            # Counts number of packets which are not malformed.
            nPackets += 1
            nPacketsByType[packet.blePacket.advType] += 1
            #if packet.blePacket.advType == 7:
            if packet.RSSI > -30 and packet.blePacket.advType == 7:
                print(packet.flags, " ", packet.blePacket.name, "-", packet.getList())

setup()
if mySniffer is not None:
    loop()

The output when the advertiser is close should be something like this:

1   "" - [32, 0, 3, 76, 166, 2, 10, 1, 37, 21, 0, 0, 91, 129, 195, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 73, 37, 32, 138, 61, 24]
1   "" - [32, 0, 3, 77, 166, 2, 10, 1, 38, 22, 0, 0, 147, 130, 195, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 73, 27, 32, 66, 120, 194]
1   "" - [32, 0, 3, 78, 166, 2, 10, 1, 39, 22, 0, 0, 203, 131, 195, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 73, 17, 32, 141, 22, 24]
17   "Test Periodic Advertising" - [68, 0, 3, 79, 166, 2, 10, 17, 9, 22, 0, 0, 206, 133, 195, 208, 214, 190, 137, 142, 7, 49, 21, 40, 117, 10, 113, 13, 192, 3, 255, 255, 255, 255, 191, 7, 101, 9, 38, 147, 65, 240, 14, 7, 26, 9, 84, 101, 115, 116, 32, 80, 101, 114, 105, 111, 100, 105, 99, 32, 65, 100, 118, 101, 114, 116, 105, 115, 105, 110, 103, 112, 184, 51]
1   "" - [32, 0, 3, 110, 166, 2, 10, 1, 37, 21, 0, 0, 223, 46, 197, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 64, 37, 32, 86, 175, 0]
1   "" - [32, 0, 3, 111, 166, 2, 10, 1, 38, 22, 0, 0, 23, 48, 197, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 64, 27, 32, 158, 234, 218]
1   "" - [32, 0, 3, 112, 166, 2, 10, 1, 39, 23, 0, 0, 79, 49, 197, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 64, 17, 32, 81, 132, 0]
17   "Test Periodic Advertising" - [68, 0, 3, 113, 166, 2, 10, 17, 0, 22, 0, 0, 82, 51, 197, 208, 214, 190, 137, 142, 7, 49, 21, 40, 117, 10, 137, 47, 192, 3, 255, 255, 255, 255, 191, 7, 101, 9, 38, 147, 65, 240, 15, 7, 26, 9, 84, 101, 115, 116, 32, 80, 101, 114, 105, 111, 100, 105, 99, 32, 65, 100, 118, 101, 114, 116, 105, 115, 105, 110, 103, 94, 111, 136]
1   "" - [32, 0, 3, 140, 166, 2, 10, 1, 39, 22, 0, 0, 18, 200, 198, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 83, 17, 32, 184, 113, 192]
17   "Test Periodic Advertising" - [68, 0, 3, 141, 166, 2, 10, 17, 19, 23, 0, 0, 21, 202, 198, 208, 214, 190, 137, 142, 7, 49, 21, 40, 117, 10, 46, 46, 192, 3, 255, 255, 255, 255, 191, 7, 101, 9, 38, 147, 65, 240, 15, 7, 26, 9, 84, 101, 115, 116, 32, 80, 101, 114, 105, 111, 100, 105, 99, 32, 65, 100, 118, 101, 114, 116, 105, 115, 105, 110, 103, 136, 25, 63]
1   "" - [32, 0, 3, 169, 166, 2, 10, 1, 37, 21, 0, 0, 135, 114, 200, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 73, 37, 32, 138, 61, 24]
1   "" - [32, 0, 3, 170, 166, 2, 10, 1, 38, 22, 0, 0, 191, 115, 200, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 73, 27, 32, 66, 120, 194]
1   "" - [32, 0, 3, 171, 166, 2, 10, 1, 39, 22, 0, 0, 247, 116, 200, 208, 214, 190, 137, 142, 71, 13, 12, 25, 157, 155, 66, 48, 47, 61, 117, 10, 73, 17, 32, 141, 22, 24]
17   "Test Periodic Advertising" - [68, 0, 3, 172, 166, 2, 10, 17, 9, 22, 0, 0, 250, 118, 200, 208, 214, 190, 137, 142, 7, 49, 21, 40, 117, 10, 192, 44, 192, 3, 255, 255, 255, 255, 191, 7, 101, 9, 38, 147, 65, 240, 15, 7, 26, 9, 84, 101, 115, 116, 32, 80, 101, 114, 105, 111, 100, 105, 99, 32, 65, 100, 118, 101, 114, 116, 105, 115, 105, 110, 103, 9, 156, 219]

Best regards
Torbjørn

[JimmyD]

my output is not the same. the loaded FW is nrf_sniffer_for_bluetooth_lev4.1.1.ut2. if this is incorrect please let me know specific what I should load.

my output is...

I ran your example_count_by_type_v2.py unmodified and got above. I never saw the characters "Test Periodic Advertising"

[ovrebekk]

Hi 

Clearly packets are received with type 7, as seen by the last value growing larger and larger, but possibly the RSSI limit of -30 is to strict in your setup. 

Could you try to change this to something lower, like -50, or just remove the RSSI check altogether? 

Alternatively try to put both kits very close together, to get a stronger signal. 

Best regards
Torbjørn

[JimmyD]

I changed the value

from -30 to -50 and got this. What does this data mean? is the MAC address hidden in this output?

[JimmyD]

I managed to get the mac address with packet.blePacket.advAddress.

However, the getList values don't match what I should be getting. Is there a command to get the extended advertising data?

[ovrebekk]

Hi Jim

To understand what the raw data means please use the Wireshark interface for reference. Here you can click on every part of the byte sequence and see exactly what it is. The first part is sniffer specific information, and the actual advertising data is located towards the end:

Just keep in mind that the raw values are output as hex in Wireshark, and as decimal in Python. 

What data is it you're missing? 

Best regards
Torbjørn

[JimmyD]

I have taken a picture of the data that I'm looking for,

This was taken from a Samsung Galaxy phone which can capture the extended advertising using your Nordic application nRFConnect. Everything after 0xFFFF> is what I'm looking for. The search parameter I entered was G4.  This was one of 5 advertising devices I need to track using Python script. I cannot correlate this data with the data I'm getting with your example program. Although I believe we are getting closer. 

[ovrebekk]

Hi Jim

Most likely the packet containing the name and the packet containing the manufacturer data is not the same. The first packet containing the name is sent on the primary advertising channels, and this will point to a larger packet sent on one of the secondary advertising channels. The mobile app compiles all the data into one view. 

Are you able to filter on the MAC address in the Python script? Then should see all the packets from the same advertiser, and verify whether or not you can see both the packets on the primary advertising channels, and the ones on the secondary advertising channel. 

Best regards
Torbjørn

[JimmyD]

Since I'm new to Bluetooth, I'll have to research this. I knew that there were channels but I haven't understood fully what they were used for or how to get that information.

Yes,  I can specifically state what MAC address to look for.

[ovrebekk]

Hi 

We provide various online courses as part of the Nordic Developer Academy, and we recently released a specific module for Bluetooth which you might want to check out:
https://www.nordicsemi.com/Support/Nordic-Developer-Academy

The short story is that Bluetooth LE uses 40 dedicated RF channels, 3 of which are designated as primary advertising channels. 

These three channels will be used for advertising only, and legacy (non extended) advertising are limited to these channels exclusively. 

The remaining 37 channels were originally only used for devices in a connection, until the extended advertising feature was introduced in v5 of the Bluetooth specification. 

An extended advertiser will essentially send a small packet on one of the primary advertising channels which contains little data, but points to a larger packet on one of the remaining 37 channels containing the payload. This means that you can advertise a large amount of data without congesting the 3 primary advertising channels, which have to be shared between all Bluetooth LE devices. 

One drawback of this mechanism (that you have to get around now) is that you need to be able to receive both the small packet sent first on one of the primary advertising channels, and the second packet sent on one of the remaining 37 channels, in order to get all the information from the advertiser. 

Best regards
Torbjørn