Bluetooth LE with nodejs on Raspberry PI - Talking to a BBC micro:bit

Tested on a Raspberry PI 3B with Rasbian Stretch Lite and RaspiOS Lite

This is just an experiment, not a full fledged library.

Installing BLUEZ

Install Prerequisites:

sudo apt-get install libusb-dev libdbus-1-dev libglib2.0-dev libudev-dev
sudo apt-get install libical-dev
sudo apt-get install libreadline-dev

Download Bluez: http://www.bluez.org/download/

wget http://www.kernel.org/pub/linux/bluetooth/bluez-5.54.tar.xz
tar -xvf bluez-5.54.tar.xz
cd bluez-5.54

Compile and install:

sudo ./configure        (--disable-systemd) ???
sudo make
sudo make install

You may now remove the folder bluez-5.54 and the .xz file if you wish.

Reboot the Pi.

Edit: /lib/systemd/system/bluetooth.service

sudo nano /lib/systemd/system/bluetooth.service

Add "--experimental" to the 'ExecStart' line:

ExecStart=/usr/local/libexec/bluetooth/bluetoothd --experimental

systemctl start bluetooth
systemctl status bluetooth

This should show 'active (running)'.

Nodejs app with NOBLE

Step 1

• First Install BLUEZ (see above)

Step 2

• Clone this repo - git clone https://github.com/DeShrike/MicroBLE.git

Step 3

• Run: npm init

  This will install noble and @abandonware/bluetooth-hci-socket

  Ignore the errors during the building of bluetooth-hci-socket

Step 4

• Edit line 6 of node_modules/noble/lib/hci-socket/hci.js like this:

var BluetoothHciSocket = require('@abandonware/bluetooth-hci-socket');

To make your own app:

npm init -y
npm install noble --save
npm install @abandonware/bluetooth-hci-socket --save

And then edit node_modules/noble/lib/hci-socket/hci.js

Step 5 - Preparing your Micro:bit

Option 1

Install MicroBLE.hex on your micro:bit.

You can also try one of the other .hex files. More info about those here:

• https://www.bluetooth.com/blog/bluetooth-bbc-microbit/
• https://github.com/lancaster-university/microbit-samples/tree/master/source/examples/bluetooth-services
• https://lancaster-university.github.io/microbit-docs/ble/profile/

After the micro:bit reboots, you should see this pattern:

Option 2 - Create your own .hex file

Go to https://makecode.microbit.org and create a new project.

Install the bluetooth services.

Create the app. Mine looks like this:

Make sure to select 'No pairing required' in the project settings.

Upload it to the micro:bit.

Beware

The micro:bit has very little memory. Adding all 6 BLE services to your app results in a memory error. If the micro:bit shows a sad face and then the number 020, it means your program is too large.

Step 6

sudo node scan.js

This will scan for Bluetooth LE devices and exit if it finds a micro:bit.

sudo node temperature.js

This will scan for Bluetooth LE devices and connect to the first micro:bit it finds and read the temperature.

sudo node fulltest.js

This script will connect to the first micro:bit it finds and send some commands to it:

• Read temperature
• Read the state of the 2 buttons
• Show a few patterns on the LED matrix
• Toggle PINs 0, 1 and 2 low/high a few times
• Wait for a few button presses

References

• https://www.youtube.com/watch?v=AFjYKEf7j2M
• https://www.youtube.com/watch?v=sP0MjQDv2N4
• http://www.bluez.org/download/
• noble/node-bluetooth-hci-socket#107
• https://github.com/noble/noble

To run without sudo:

sudo setcap cap_net_raw+eip $(eval readlink -f `which node`)

Using bluetoothctl

You can use this tool to browse the BLE services of a device.

sudo bluetoothctl

power on
scan on
scan off
devices
connect DD:82:10:FF:52:5E               <- add the address of your device here
menu gatt
select-attribute /org/bluez/hci0/dev_DD_82_10_FF_52_5E/service0013       <- sample
attribute-info
back
disconnect
power off
exit

TODO

Reading of the Accelerometer and Magnetometer is not implemented (yet).

server.js is a WIP