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A BLE -> MQTT bridge for Raspberry Pi and other Embedded devices
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gfwilliams Merge pull request #34 from palortoff/fix-discovery
fix discovery in ide when using remote mqtt server
Latest commit e6aecba Dec 11, 2019


A BLE -> MQTT bridge for Raspberry Pi and other Embedded devices for Espruino and Puck.js

Setting up

Ideally use a Raspberry Pi 3 or Zero W, as these have Bluetooth LE on them already. However the BLE USB dongles mentioned in the Puck.js Quick Start guide should work.

Get Raspbian running on your Raspberry Pi

  • Download Raspbian Lite from
  • Copy it to an SD card with sudo dd if=2017-11-29-raspbian-stretch-lite.img of=/dev/sdc status=progress bs=1M on Linux (or see the instructions on the Raspbian download page above for your platform)
  • Unplug and re-plug the SD card and add a file called ssh to the boot drive - this will enable SSH access to the Pi
  • If you're using WiFi rather than Ethernet, see this post on setting up WiFi via the SD card
  • Now put the SD card in the Pi, apply power, and wait a minute
  • ssh pi@raspberrypi.local (or use PuTTY on Windows) and use the password raspberry
  • Run sudo raspi-config and set the Pi up as you want (eg. hostname, password)

Installation of everything (EspruinoHub, Node-RED, Web IDE)

These instructions install up to date Node.js and Node-RED - however it can take a while! If you just want EspruinoHub and the IDE, see the next item.

sudo apt-get update
sudo apt-get install build-essential python-rpi.gpio nodejs nodered
# OPTIONAL: Install a modern version of nodejs and nodered
# Not recommended - The Pi's supplied Node.js version is more than good enough
# bash <(curl -sL
# Get dependencies
sudo apt-get install mosquitto mosquitto-clients bluetooth bluez libbluetooth-dev libudev-dev
# Auto start Node-RED
sudo systemctl enable nodered.service
# Start nodered manually this one time (this creates ~/.node-red)
sudo systemctl start nodered.service
# Install the Node-RED UI
cd ~/.node-red && npm install node-red-contrib-ui
# Now get EspruinoHub
cd ~/
git clone
# Install EspruinoHub's required Node libraries
cd EspruinoHub
npm install
# Optional - enable gathering of historical data by creating a 'log' directory
mkdir log
# Give Node.js access to Bluetooth
sudo setcap cap_net_raw+eip $(eval readlink -f `which node`)

You can now type ./ to run EspruinoHub, but it's worth checking out the Auto Start section to see how to get it to run at boot.

Installation of EspruinoHub and Web IDE

# Install Node, Bluetooth, etc
sudo apt-get update
sudo apt-get install git-core nodejs npm build-essential mosquitto mosquitto-clients bluetooth bluez libbluetooth-dev libudev-dev
# Now get EspruinoHub
git clone
# Install EspruinoHub's required Node libraries
cd EspruinoHub
npm install
# Optional - enable gathering of historical data by creating a 'log' directory
mkdir log
# Give Node.js access to Bluetooth
sudo setcap cap_net_raw+eip $(eval readlink -f `which node`)

You can now type ./ to run EspruinoHub, but it's worth checking out the Auto Start section to see how to get it to run at boot.

Auto Start

There are a 2 main ways to run EspruinoHub on the Raspberry Pi.

Headless Startup

This is the normal way of running services - to configure them as a system start-up job using systemd:**

    sudo cp systemd-EspruinoHub.service /etc/systemd/system/EspruinoHub.service

and edit it as necessary to match your installation directory and user configuration. Then, to start it for testing:

    sudo systemctl start EspruinoHub.service && sudo journalctl -f -u EspruinoHub

If it works, Ctrl-C to break out and enable it to start on login:

    sudo systemctl enable EspruinoHub.service

Console Startup

If you have a video output on your Pi then you can run EspruinoHub at boot - on the main display - so that you can see what it's reporting.

  • Edit .bashrc and add the following right at the bottom:
if [ $(tty) == /dev/tty1 ]; then
  while true; do
    sleep 1s
  • Now run sudo raspi-config, choose Boot Options, Desktop / CLI, and Console Autologin

  • Next time you reboot, the console will automatically run EspruinoHub


  • On non-Raspberry Pi devices, Mosquitto (the MQTT server) may default to not allowing anonymous (un-authenticated) connections to MQTT. To fix this edit /etc/mosquitto/conf.d/local.conf and set allow_anonymous to true.
  • By default the HTTP server in EspruinoHub is enabled, however it can be disabled by setting http_port to 0 in config.json
  • The HTTP Proxy service is disabled by default and needs some configuration - see HTTP Proxy below
  • You used to need a local copy of the Espruino Web IDE, however now EspruinoHub just serves up an IFRAME which points to the online IDE, ensuring it is always up to date.


Assuming you followed the steps above (including for 'Headless Startup') you can uninstall EspruinoHub using the following commands:

sudo systemctl stop EspruinoHub.service
sudo systemctl disable EspruinoHub.service
sudo rm /etc/systemd/system/EspruinoHub.service
sudo rm -rf ~/EspruinoHub


Once started, you then have a few options...

Status / Websocket MQTT / Espruino Web IDE

By default EspruinoHub starts a web server at http://localhost:1888 that serves the contents of the www folder. You can disable this by setting http_port to 0 in config.json.

With that server, you can:


If set up, you can access Node-RED using http://localhost:1880

Once you add UI elements and click Deploy they'll be visible at http://localhost:1880/ui

The easiest way to get data is to add an MQTT listener node that requests /ble/advertise/# (# is a wildcard). This will output all information received via advertising (see 'Advertising Data' below).

For more info on available MQTT commands see the 'MQTT Bridge' section below.

Check out for a proper introduction on using Node-RED.

MQTT Command-line

You can use the Mosquitto command-line tools to send and receive MQTT data that will make EspruinoHub do things:

# listen to all, verbose
mosquitto_sub -h localhost -t "/#" -v

# listen to any device advertising a 1809 temperature characteristic and
# output *just* the temperature
mosquitto_sub -h localhost -t "/ble/advertise/+/temp"

# Test publish
mosquitto_pub -h localhost -t test/topic -m "Hello world"

For more info on available MQTT commands see the 'MQTT Bridge' section below.

MQTT bridge


Data that is received via bluetooth advertising will be relayed over MQTT in the following format:

  • /ble/presence/DEVICE - 1 or 0 depending on whether device has been seen or not
  • /ble/advertise/DEVICE - JSON for device's broadcast name, rssi and manufacturer-specific data
  • /ble/advertise/DEVICE/manufacturer/COMPANY - Manufacturer-specific data (without leading company code) encoded in base16. To decode use var data = Buffer.from(msg.payload, 'hex');
  • /ble/advertise/DEVICE/rssi - Device signal strength
  • /ble/advertise/DEVICE/SERVICE - Raw service data (as a JSON Array of bytes)
  • /ble/advertise/DEVICE/PRETTY or /ble/PRETTY/DEVICE - Decoded service data based on the decoding in attributes.js
    • 1809 decodes to temp (Temperature in C)
    • 180f decodes to battery
    • feaa decodes to url (Eddystone)
    • 2a6d decodes to pressure (Pressure in pa)
    • 2a6e decodes to temp (Temperature in C)
    • 2a6f decodes to humidity (Humidity in %)
    • ffff decodes to data (This is not a standard - however it's useful for debugging or quick tests)
  • /ble/advertise/DEVICE/espruino - If manufacturer data is broadcast Espruino's manufacturer ID 0x0590 and it is valid JSON, it is rebroadcast. If an object like {"a":5,"b":10} is sent, /ble/advertise/DEVICE/a and /ble/advertise/DEVICE/b will also be sent. (A JSON5 parser is used, so the more compact {a:5,b:10} is also valid).

You can take advantage of Espruino's manufacturer ID 0x0590 to relay JSON over Bluetooth LE advertising using the following code on an Espruino board:

var data = {a:1,b:2};

Assuming a device with an address of ma:c_:_a:dd:re:ss this will create the folling MQTT topics:

  • /ble/advertise/ma:c_:_a:dd:re:ss/espruino -> {"a":10,"b":15}
  • /ble/advertise/ma:c_:_a:dd:re:ss/a -> 1
  • /ble/advertise/ma:c_:_a:dd:re:ss/b -> 2

Note that you only have 24 characters available for JSON, so try to use the shortest field names possible and avoid floating point values that can be very long when converted to a String.


You can also connect to a device using MQTT packets:

  • /ble/write/DEVICE/SERVICE/CHARACTERISTIC connects and writes to the charactertistic
  • /ble/read/DEVICE/SERVICE/CHARACTERISTIC connects and reads from the charactertistic, sending the result back as a topic /ble/data/DEVICE/SERVICE/CHARACTERISTIC
  • /ble/read/DEVICE connects and reads an array of services and charactertistics
  • /ble/notify/DEVICE/SERVICE/CHARACTERISTIC connects and starts notifications on the characteristic, which send data back on /ble/data/DEVICE/SERVICE/CHARACTERISTIC
  • /ble/ping/DEVICE connects, or maintains a connection to the device, and sends /ble/pong/DEVICE on success

SERVICE and CHARACTERISTIC are either known names from attributes.js such as nus and nus_tx or are of the form 6e400001b5a3f393e0a9e50e24dcca9e for 128 bit uuids or abcd for 16 bit UUIDs.

After connecting, EspruinoHub will stay connected for a few seconds unless there is any activity (eg a write or ping). So you can for instance evaluate something on a Puck.js BLE UART connection with:

=> /ble/notify/c7:f9:36:dd:b0:ca/nus/nus_rx
"\x10Bluetooth.println(E.getTemperature())\n" => /ble/write/c7:f9:36:dd:b0:ca/nus/nus_tx

/ble/data/c7:f9:36:dd:b0:ca/nus/nus_rx => "23\r\n"

Once a /ble/write/DEVICE/SERVICE/CHARACTERISTIC has been executed, a /ble/written/DEVICE/SERVICE/CHARACTERISTIC packet will be sent in response.


EspruinoHub contains code (libs/history.js) that subscribes to any MQTT data beginning with /ble/ and that then stores logs of the average value every minute, 10 minutes, hour and day (see config.js:history_times). The averages are broadcast over MQTT as the occur, but can also be queried by sending messages to /hist/request.

For example, an Espruino device with address f5:47:c8:0b:49:04 may broadcast advertising data with UUID 1809 (Temperature) with the following code:

setInterval(function() {
    0x1809 : [Math.round(E.getTemperature())]
}, 30000);

This is decoded into temp by attributes.js, and it sends the following MQTT packets:

/ble/advertise/f5:47:c8:0b:49:04 {"rssi":-53,"name":"...","serviceUuids":["6e400001b5a3f393e0a9e50e24dcca9e"]}
/ble/advertise/f5:47:c8:0b:49:04/rssi -53
/ble/advertise/f5:47:c8:0b:49:04/1809 [22]
/ble/advertise/f5:47:c8:0b:49:04/temp 22
/ble/temp/f5:47:c8:0b:49:04 22

You can now subscribe with MQTT to /hist/hour/ble/temp/f5:47:c8:0b:49:04 and every hour you will receive a packet containing the average temperature over that time.

However, you can also request historical data by sending the JSON:

  "topic" : "/hist/hour/ble/temp/f5:47:c8:0b:49:04",
  "interval" : "minute",
  "age" : 6  

to /hist/request/a_unique_id. EspruinoHub will then send a packet to /hist/response/a_unique_id containing:

  "from":1531227216903, // unix timestamp (msecs since 1970)
  "to":1531234416903,   // unix timestamp (msecs since 1970)
  "times":[ array of unix timestamps ],
  "data":[ array of average data values ]

Requests can be of the form:

  topic : "/ble/advertise/...",
  "interval" : "minute" / "tenminutes" / "hour" / "day"
  // Then time period is either:
  "age" : 1, // hours
  // or:
  "from" : "1 July 2018",
  "to" : "5 July 2018"     (or anything that works in new Date(...))  

For a full example of usage see www/rssi.html.

HTTP Proxy

EspruinoHub implements the Bluetooth HTTP Proxy service

The HTTP Proxy is disabled by default as it can give any Bluetooth LE device in range access to your network. To fix this, edit the http_proxy and http_whitelist entries in config.json to enable the proxy and whitelist devices based on address (which you can find from EspruinoHub's status of MQTT advertising packets).

To allow Bluetooth to advertise services (for the HTTP proxy) you also need:

# Stop the bluetooth service
sudo service bluetooth stop
# Start Bluetooth but without bluetoothd
sudo hciconfig hci0 up



When using the HTTP Proxy I get BLOCKED returned in the HTTP body

Your BLE device isn't in the whitelist in config.json - because the HTTP Proxy exposes your internet connection to the world, only BLE devices with the addresses you have specified beforehand are allowed to connect.


  • Handle over-size reads and writes for HTTP Proxy
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