Nespresso Expert machine has Bluetooth ability which officially can be used only by Nespresso mobile app and it does not offer any API for 3rd party applications and services. Moreover, the Bluetooth services and characteristics are not documented and are easy to use by the other Bluetooth libraries plus there is no documentation for the Bluetooth packets payload that needs to be sent or received.

However, after searching a lot and sniffing the packets for a couple of days, I've been able to hack the machine and write the small Nodejs application using noble and express to control and monitor the machine with Rest API exposed by express through Bluetooth connection. As I did this application for my ex-company I cannot share the code but I'm going to explain how it works.

Thanks to this repo and also this nice medium post that basically helped me to understand how I need to sniff the packets.

Sniffing

First, I have installed the Nespresso app on my mobile and I connected to the machine and start using the application. Then, I sniffed the packets and opened them in the Wireshark to analyze them.

Authentication

I noticed every time on the app we start communicating with the machine (brew or monitor or just opening machine tab) it starts the conversation with a packet that has "8" at the start of its value and has 16 characters (mine was 85c55bc324a4170b) and it is writing on the 4th characteristic of the service 06aa1910f22a11e39daa0002a5d5c51b.
note: only one mobile can connect to the expert machine and every time that new mobile connects (which needs the device reset) the authentication packet will change.
I have used noble library for ble communication. I mention some hints ;) Authentication will be done by writing to 4th characteristic of the first service Buffer.from("85c55bc324a4170b", "hex"). after writing when you read the 5th characteristic, the data should be "2" which means authentication was successful.

Communication

I don't know why but before sending the brew command you need to write this Buffer.from("01100800000200c8000000", "hex") on the 4th character of the second service ("06aa1920f22a11e39daa0002a5d5c51b") and then inside the callback, you write this Buffer.from("03050704000000000101", "hex") which is low temp espresso. Now your machine should start brewing!!!

Brewing Types

Here are my observations:
0305070400000000 00 00 medium ristretto
0305070400000000 01 01 low espresso
0305070400000000 02 02 high lungo
0305070400000000 01 04 low hot water
0305070400000000 01 05 low americano
0305070400000000 01 07 low probably cleaning mode (all lights turning on together)
03060102 would stop the brewing (not always)

Machine Alarms (Errors)

On the second service, on 0th character read normally is like 0:64 1:9 2:13 3:64 4:128 5:0 6:255 7:255.
0: 64 is ok, 65: no water
1: 64 with 132 is brewing or busy, 64 with 2 ready, 64 with 66/67/7x :full disposal or no disposal on the second service, on 4th character read normally is like: 0:129 1:16 2:1 3:32 4:0 5:0 6:0 7:0 8:0 9:0 10:0 11:0 12:0 13:0 14:0 15:0 16:0 17:0 18:0 19:0

For understanding slide error, read should be done after the command of brew
1: 195 slider error, 129 ok, 131 busy brewing

What you can do now?

What we have done was connecting it with an Alexa app and brewing coffee by asking Alexa to "make us a coffee". In fact, we added a box with different types of coffee capsules and made it cool for the demo but anyway you can just use the Alexa to brew you a coffee in the morning :)

Check out this gist at https://gist.github.com/farminf/94f681eaca2760212f457ac59da99f23