Author: BleuIO

Bluetooth ranging technology is very popular. There are many localization systems that exist based on beacons. Beacon technology usually estimates the distance between devices using the received signal strength (RSSI). 

Bluetooth can be an excellent way to narrow down a search area at close distances when tracking something. This feature can be used in several fields. such as Secure Locks for Buildings and Automotive, Asset localization & tracking, Indoor navigation etc

GPS tracking isn’t excellent at giving accurate measurements of the close distance, especially in the indoor environment. On the other hand, Bluetooth is excellent in short ranges because the waves can go through walls. This might fill the gap that GPS tracking has when tracking devices in indoor spaces.

However, most calculations of the distance between two Bluetooth devices are estimates. It’s hard to determine the exact distance between two Bluetooth devices because many factors affect the calculations. Despite the challenges, there are methods to determine the distance between two Bluetooth devices with an accuracy of at least 80%.

The ranging method is simple to implement, and it has the formula to calculate the distance between two Bluetooth devices. As the name suggests, both devices need to be within Bluetooth range to estimate the distance. 

This article will share a simple python script to determine nearby Bluetooth devices and their distance in meters.

This script scans for nearby Bluetooth devices and gets an approximation of the distance by using the well-known RSSI to distance formula.

Read more about how to calculate the distance

Requirments 

• Bluetooth Low Energy USB dongle BleuIO (https://www.bleuio.com)
• Pyserial.

Instructions

• Get the script from GitHub at https://github.com/smart-sensor-devices-ab/python_bluetooth_device_distance_meter.git
• Connect the BleuIO to your computer. The script uses pyserial to connect to the Bluetooth USB dongle BleuIO.
• Update the script and write the correct COM port, where the dongle is connected. 
• After connecting to the dongle, we put the dongle into the central role so that it can scan for nearby Bluetooth devices. 
• Then we do a simple Gap scan using AT+GAPSCAN=3 command to scan for nearby Bluetooth devices for 3 seconds.
• After that, we read the output from the serial port and use our RSSI to distance formula to get the distance in meters. 
• Finally, we sort the result by distance before printing it out on screen.

Here is the final script file. 

import serial
import time

your_com_port = "COM18"  # Change this to the com port your dongle is connected to.
connecting_to_dongle = True

print("Connecting to dongle...")
# Trying to connect to dongle until connected. Make sure the port and baudrate is the same as your dongle.
# You can check in the device manager to see what port then right-click and choose properties then the Port Settings
# tab to see the other settings

while connecting_to_dongle:
    try:
        console = serial.Serial(
            port=your_com_port,
            baudrate=57600,
            parity="N",
            stopbits=1,
            bytesize=8,
            timeout=0,
        )
        if console.is_open.__bool__():
            connecting_to_dongle = False
    except:
        print("Dongle not connected. Please reconnect Dongle.")
        time.sleep(5)

print("Connected to Dongle.")

# function to convert rssi to distance in meter
def rssiToDistance(rssi):    
  n=2
  mp=-69
  return round(10 ** ((mp - (int(rssi)))/(10 * n)),2)    

#put the dongle in dual role, so we can scan for nearby device
console.write(str.encode("AT+CENTRAL"))
console.write("\r".encode())
print("Putting dongle in Central role.")
time.sleep(0.1)
# Scan for nearby devices for 3 seconds
console.write(str.encode("AT+GAPSCAN=3"))
console.write("\r".encode())
time.sleep(0.1)
print("Looking for nearby Bluetooth devices ...")
dongle_output2 = console.read(console.in_waiting)
time.sleep(3)
print("Scan Complete!")
filtered = []
# Filter out unncecssary outputs and keep only the list of devices (also remove index)
for dev in dongle_output2.decode().splitlines():
    if len(dev)>20:
        filtered.append(dev.split(maxsplit=1)[1])
# Get unique device by device id and add distance to each raw        
seen = set()
out = []
for elem in filtered:
    prefix = elem.split(' ')[1]
    if prefix not in seen:
        seen.add(prefix)
        out.append(elem + " Distance: "+str(rssiToDistance(elem.split()[3]))+" meter") 

# sort list by closest device
out.sort(key=lambda x:int(x.split()[3]),reverse=True)

# print(out)
for i in range(0, len(out)):
    print (out[i]) 

time.sleep(0.1)
console.close()

Output

After running the script, we see a total 20 devices found nearby. The list shows their distance in meter from the central device.

There are so many Bluetooth-enabled smart devices that it can be confusing how the technology connects the devices. Often we want to connect to multiple peripheral devices simultaneously to get advertised packets or do other operations. In this article, we will see how we can get advertised packets from two different Air quality monitoring sensor devices. 

For this project, we will use Chrome Web serial API to connect to a Bluetooth USB dongle. Using the serial port read/write operation we will scan for specific device advertised data and filter out what we need. After that, we decode the advertised packet to meaningful air quality data using the device documentation.

Requirments

1. BleuIO Bluetooth USB dongle x1
2. HibouAir Air quality monitor x2

Steps

At first, we will get the bleuIO javascript library from NPM. This library will help us easily connect to the serial port,wtire AT commands and read responses in real-time.

Type npm i bleuio on the command prompt of your project root folder.

After that, we create two files. index.html and script.js

Index.html will be responsible for the output and layouts of the project. 

Script.js will have the programming and logic to connect to the dongle and read/write data.

There will be two buttons connect and get data.

The connect button will connect to the bleuIO dongle using the serial port. 

The get data button will do several tasks.

At first, we put the dongle in a dual role (central mode) so that it can scan for peripheral devices. Then we will look for advertised data with their sensor ID one after another. 

Using the documentation from the air quality device, we decode the advertised data.

Finally, we print it out on the screen.

Here is the index.html file code

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <title>Bootstrap demo</title>
    <link
      href="https://cdn.jsdelivr.net/npm/bootstrap@5.2.0-beta1/dist/css/bootstrap.min.css"
      rel="stylesheet"
      integrity="sha384-0evHe/X+R7YkIZDRvuzKMRqM+OrBnVFBL6DOitfPri4tjfHxaWutUpFmBp4vmVor"
      crossorigin="anonymous"
    />
  </head>
  <body>
    <div class="container mt-5">
      <h1>Get air quality Bluetooth LE sensor data from multiple devices</h1>
      <br /><br /><br /><button
        id="connect"
        class="btn btn-success btn-lg me-5"
      >
        Connect
      </button>
      <button id="getData" class="btn btn-warning btn-lg ms-5">Get Data</button>
      <br />
      <br />
      <div id="loading" style="display: none">Fetching Data ...</div>
      <br />
      <div id="airData"></div>
    </div>

    <script src="script.js"></script>
  </body>
</html>

Here is script.js file code

import * as my_dongle from 'bleuio'
document.getElementById('connect').addEventListener('click', function(){
  my_dongle.at_connect()
  document.getElementById("connect").classList.add('disabled');
})
let dev1BoardID='45840D'
let dev2BoardID='60FDED'
document.getElementById('getData').addEventListener('click', function(){
    
    //show loading
    document.getElementById("loading").style.display = "block";
    //make the dongle in dual role , so it can scan for peripheral devices advertised data
    my_dongle.at_dual().then(()=>{
        //scan for a devices advertised data, a PM sensor
        my_dongle.at_findscandata(dev1BoardID,8).then((x)=>{
            //it returns an array of advertised data
            //from the array, we take the last one
            //it looks like this "[F9:0D:35:E7:72:65] Device Data [ADV]: 0201061BFF5B07050345840DB1031527FB002A010402040004000400000001"
            //then we split it by space
            //so we can get the advertised data only (the last part)
            return x[x.length-1].split(" ").pop()
        }).then((adv1)=>{ 
            //now lets decode the advertised data for this device using the device documentaion
            let pmEnvData=advDataDecode(adv1)
            //we do the same process to get advertised data of another device
            //after waiting 1 seconds
            setTimeout(()=>{
                my_dongle.at_findscandata(dev2BoardID,8).then((y)=>{
                    let adv2= y[y.length-1].split(" ").pop()
                    //again we decode the advertised data for this device using the device documentaion
                    let co2EnvData=advDataDecode(adv2)
                    //now merge pm data to this array
                    co2EnvData.pm1=pmEnvData.pm1
                    co2EnvData.pm25=pmEnvData.pm25
                    co2EnvData.pm10=pmEnvData.pm10
                    document.getElementById('airData').innerHTML=`
                    Air Quality data from PM and CO2 sensor devices<br/><br/>
                    CO2 : ${co2EnvData.co2} ppm<br/>
                    PM 1.0 : ${co2EnvData.pm1} µg/m³<br/>
                    PM 2.5 : ${co2EnvData.pm25} µg/m³<br/>
                    PM 10 : ${co2EnvData.pm10} µg/m³<br/>
                    Temperature : ${co2EnvData.temp} °C<br/>
                    Humidity : ${co2EnvData.hum} %rH<br/>
                    Pressure : ${co2EnvData.pressure} mbar<br/>
                    Light : ${co2EnvData.light} Lux<br/>

                    `
                    //hide loading
                    document.getElementById("loading").style.display = "none"; 
                })
            },1000)
            
        })
    })
    

  })

  const advDataDecode =((data)=>{
    let pos = data.indexOf("5B0705")
    let dt = new Date();
    let currentTs = dt.getFullYear() 
    + '/' 
    + (dt.getMonth() + 1).toString().padStart(2, "0") 
    + '/' 
    + dt.getDate().toString().padStart(2, "0")
    +' '
    +
    dt.getHours().toString().padStart(2, "0")
    +
    ':'
    +
    dt.getMinutes().toString().padStart(2, "0")
    +
    ':'
    +dt.getSeconds().toString().padStart(2, "0")
    let tempHex=parseInt('0x'+data.substr(pos+22,4).match(/../g).reverse().join(''))
    if(tempHex>1000)
        tempHex = (tempHex - (65535 + 1) )/10
    else
        tempHex = tempHex/10
    return {
      "boardID":data.substr(pos+8,6),
      "type":data.substr(pos+6,2),
      "light":parseInt('0x'+data.substr(pos+14,4).match(/../g).reverse().join('')),
      "pressure":parseInt('0x'+data.substr(pos+18,4).match(/../g).reverse().join(''))/10,
      "temp":tempHex,
      "hum":parseInt('0x'+data.substr(pos+26,4).match(/../g).reverse().join(''))/10,
      "pm1":parseInt('0x'+data.substr(pos+34,4).match(/../g).reverse().join(''))/10,
      "pm25":parseInt('0x'+data.substr(pos+38,4).match(/../g).reverse().join(''))/10,
      "pm10":parseInt('0x'+data.substr(pos+42,4).match(/../g).reverse().join(''))/10,
      "co2":parseInt('0x'+data.substr(pos+46,4)),
      "ts":currentTs
    }
})

Source code also available on github

https://github.com/shuhad/bluetooth_mutiple_device_read

Run the script

You can either clone the script from github or follow the instructions and make a new project.

For this project to run we may need a web build tool. I prefer using parcel.

https://parceljs.org/

install parcel if you don’t have

npm install --save-dev parcel

Now run the script using

parcel index.html

Output

The script can be modified to read more than two devices as required.

Home automation involves automating household environment equipment. To achieve that, we have created a smart bulb that can be controlled remotely using smart phone app. The aim of this project is to control different home appliances using smartphone at your home.

Introduction

This example is showing how to control a GPIO pin on a RaspberryPi remotely from a smart phone (or another BleuIO Dongle).

For this example we will need:

• A RaspberryPi
• A BleuIO Dongle (https://www.bleuio.com/)
• Our example python script (https://github.com/smart-sensor-devices-ab/bleuio_rpi_switch_example)
• A way to connect to the GPIO Pin (Like a 5V Relay and a Lightbulb)

WARNING – THIS PROJECT INVOLVES HIGH VOLTAGES THAT CAN CAUSE SERIOUS INJURY OR DEATH. PLEASE TAKE ALL NECESSARY PRECAUTIONS, AND TURN OFF ALL POWER TO A CIRCUIT BEFORE WORKING ON IT.

Connecting the relay

Beware:

Always be very careful when experimenting with AC, electrical shock can result in serious injuries! NOTICE OF RISK; DISCLAIMER OF LIABILITY

Instructions for bleuio_rpi_switch_example.py

• Connect the BleuIO Dongle to your RaspberryPi.
• Edit the variable ‘switch’ in the script to the GPIO pin you want to use. (You can use the command pinout to get a graphical view showing you the GPIO pins for the board)

• Finally just run python script and and use your phone to connect to the BleuIO Dongle and send on/off messages to controll the GPIO!

Instructions for connecting to the BleuIO from mobile

• Download a BLE scanning App that can connect and read/write to a device. (Like nRFConnect or BLEScanner)
  Android, IOS

• Look for the dongle, it will be advertising as ‘BleuIO’.

• Connect to the BleuIO Dongle.

• To enable BleuIO to recieve commands you must first write 0x01 to the Flow Control characteristic (UUID: 0783b03e-8535-b5a0-7140-a304d2495cb9)

• Now you can write to the Server RX Data characteristic (UUID: 0783b03e-8535-b5a0-7140-a304d2495cba) to control the GPIO.
  |CMD|Effect|
  |–|–|
  |“SW=1”| ON|
  |“SW=0”| OFF|

The script

Here is the python script that receives the messages from smart phone app and helps control the light.

#!/usr/bin/python3
# Copyright 2022 Smart Sensor Devices in Sweden AB
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
# The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

import time
import serial.tools.list_ports
import serial
import RPi.GPIO as io


switch = 7  # Edit this to suit your setup! (7 = GPIO 04), use command pinout to graphically show you the GPIO pins for the board
io.setmode(io.BOARD)
io.setup(switch, io.OUT)

master_array = []
index = 1
dongle_port = ""

print("\nWelcome to BleuIO RaspberryPi Switch Example!\n")

print("\nPlease insert dongle...")
try:
    while len(master_array) == 0:
        m_ports = serial.tools.list_ports.comports(include_links=False)
        for port in m_ports:
            if str(port.hwid).__contains__("VID:PID=2DCF"):
                master = port.device + " " + port.hwid
                if master.__contains__("VID:PID=2DCF:6002"):
                    print("Found dongle in port: %s" % port.device)
                    master_array.append(master)
                    dongle_port = port
                    break

    for dongle in master_array:
        print("\nConnecting to BleuIO @ %s\n" % dongle)

    time.sleep(0.5)
    dongle_conn = serial.Serial(
        dongle_port.device,
        115200,
        timeout=1,
    )

    if not dongle_conn.is_open:
        dongle_conn.open()

    print("Starting Advertising...")
    dongle_conn.write("AT+GAPDISCONNECTALL\rAT+DUAL\rAT+ADVSTART\rATI\r".encode())
    read_tries = 0
    dongle_resp = ""
    while read_tries < 20:
        dongle_resp = dongle_conn.readline().decode()
        if "Not Advertising" in dongle_resp:
            dongle_conn.write("AT+ADVSTART\r")
        if b"Advertising\r\n" in dongle_resp.encode():
            break
        read_tries += 1
        time.sleep(0.01)

    if dongle_resp:
        print("BleuIO is %s" % dongle_resp)
    else:
        print("ERROR! No response...")
        exit()

    print(
        "Going into loop, waiting for signal to turn switch on/off...\n(Press Ctrl+C to abort)"
    )
    while True:
        try:
            dongle_resp = dongle_conn.readline().decode()
            if "SW=0" in dongle_resp:
                print("Turn Switch off!")
                io.output(switch, io.LOW)
            if "SW=1" in dongle_resp:
                print("Turn Switch on!")
                io.output(switch, io.HIGH)
        except KeyboardInterrupt:
            if dongle_conn.is_open:
                dongle_conn.write("AT+GAPDISCONNECTALL\rAT+ADVSTOP\r".encode())
                dongle_conn.close()
                io.cleanup()
            print("\nBye!")
            exit()

except Exception as e:
    print("(ERROR: %s)" % (e))

Output

We have tested the script using nRFConnect app from both IOS and Android phone to turn on/off the light bulb. Here is the output of this project.

Introduction

Here we will describe two quick ways of measuring the data throughput of the BleuIO Dongle.
For both examples we are going to need a BleuIO Dongle, another Bluetooth device (like another Bleuio Dongle) and a computer with Python (minimum version: 3.6) installed.

For the first measurement example, measuring the BLE data throughput, you will need one of the following supported development kits from Nordic Semiconductor:

• nRF52840 DK (PCA10056)
• nRF52840 Dongle (PCA10059)
• nRF52833 DK (PCA10100)
• nRF52 DK (PCA10040)
• nRF51 DK (PCA10028)
• nRF51 Dongle (PCA10031)

The first measurement example is the actual BLE data throughput. For this we will use a BleuIO Dongle and Wireshark. (For help on how to setup Wireshark and requirements go to this link: https://infocenter.nordicsemi.com/topic/ug_sniffer_ble/UG/sniffer_ble/intro.html ).
We will also utilize a simple python script that sends a set amount of data. For this measurement you can ignore the throughput print at the end of the script.

The second measurement example is for measuring the actual data being transferred over the USB as a Virtual COM port (via the CDC protocol).
We will be using the same simple script that will send a set amount of data and time when the transfer starts and then stops. Then divide the amount of data with the time the transfer took to get the throughput.

Notice : Interference can be caused by other wireless networks, other 2.4 GHz frequency devices, and high voltage devices that generate electromagnetic interference. This have impact on the measurement of throughput. To avoid interference, select wireless free space or use a shield box.

Instructions for BLE data throughput

• For best result place the nRF Dev Kit between the BleuIO Dongle and your target device.
• Open Wireshark and double-click the ‘nRF Sniffer for Bluetooth LE’.

• Make sure the target Bluetooth device is advertising and find in the the scroll-down list.

• Choose ‘IO/Data’ under the ‘Analysis’ menu tab.

• Click the ‘+’ button to add new graphs. Add ‘bytes per seconds’ and/or ‘bit per seconds’.

• Modify the script by filling in the relevant information into the variables ‘your_com_port’, ‘target_mac_addr’ and ‘write_handle’.
• Run the python script.
• You can now observe the graph showing the BLE Data throughput!

Instructions for USB port data throughput

This is the second measurement example for measuring the actual point to point data transfer between the two USB ports.

• Connect the dongle to your computer. (Look up the COM port your dongle uses and paste it in the script in the variable ‘your_com_port’)
• Scan (Using AT+GAPSCAN) after the device you wish to send the data to. Copy the mac address of the device into the script in the variable ‘target_mac_addr’.
• Connect to the device and look up the handle of the characteristic you want to write to and paste into the script in the variable ‘write_handle’.
• Finally just run python script and the throughput will be displayed at the end!

The script

import datetime
import serial
import time
import string
import random

connecting_to_dongle = True
trying_to_connect = False

# Change this to the com port your dongle is connected to.
your_com_port = "COM20"
# Change this to the mac address of your target device.
target_mac_addr = "[0]40:48:FD:E5:2C:F2"
# Change this to the handle of the characteristic on your target device.
write_handle = "0011"

# You can experiment with the packet length, increasing or decreasing it and see how that effect the throughput
packet_length = 150
# 1 Megabytes = 1000000 Bytes
file_size = 0.5 * 1000000
end_when = file_size / packet_length
send_counter = 0

# Random data string generator
def random_data_generator(size=packet_length, chars=string.digits + string.digits):
    return "".join(random.choice(chars) for _ in range(size))


print("Connecting to dongle...")
while connecting_to_dongle:
    try:
        console = serial.Serial(
            port=your_com_port,
            baudrate=115200,
            parity="N",
            stopbits=1,
            bytesize=8,
            timeout=0,
        )
        if console.is_open.__bool__():
            connecting_to_dongle = False
    except:
        print("Dongle not connected. Please reconnect Dongle.")
        time.sleep(5)

print("Connected to Dongle.")
console.write(str.encode("AT+GAPDISCONNECT\r"))
start = input("Press Enter to start.\n\r>> ")

console.write(str.encode("ATE0\r"))
console.write(str.encode("AT+DUAL\r"))
connected = "0"
while connected == "0":
    time.sleep(0.5)
    if not trying_to_connect:
        # change to Mac address of the device you want to connect to
        console.write(str.encode("AT+GAPCONNECT=" + target_mac_addr + "\r"))
        trying_to_connect = True
    dongle_output2 = console.read(console.in_waiting)
    time.sleep(2)
    print("Trying to connect to Peripheral...")
    if not dongle_output2.isspace():
        if dongle_output2.decode().__contains__("\r\nCONNECTED."):
            connected = "1"
            print("Connected!")
            time.sleep(8)
        if dongle_output2.decode().__contains__("\r\nDISCONNECTED."):
            connected = "0"
            print("Disconnected!")
            trying_to_connect = False
        dongle_output2 = " "

start2 = input("Press Enter to sending.\n\r>> ")
start_time = time.mktime(datetime.datetime.today().timetuple())
console.write(
    str.encode(
        "AT+GATTCWRITEWRB=" + write_handle + " " + random_data_generator() + "\r"
    )
)
while 1:
    dongle_output = console.read(console.in_waiting)
    if send_counter > end_when:
        end_time = time.mktime(datetime.datetime.today().timetuple())
        break
    # Change to the handle of the characteristic you want to write to
    if "handle_evt_gattc_write_completed" in str(dongle_output):
        console.write(
            str.encode(
                "AT+GATTCWRITEWR=" + write_handle + " " + random_data_generator() + "\r"
            )
        )
        send_counter = send_counter + 1
    try:
        if not dongle_output.decode() == "":
            print(dongle_output.decode())
    except:
        print(dongle_output)

time_elapsed = end_time - start_time
time.sleep(0.1)

print("*" * 25)
print("Transfer Complete in: " + str(time_elapsed) + " seconds")
print(str(packet_length * send_counter) + "bytes sent.")
print("*" * 25)
print(
    "Throughput via USB (Virtual COM port): "
    + str((packet_length * send_counter) / time_elapsed)
    + " Bytes per seconds"
)
print("*" * 25)