This project allows me to make espresso using an unexpensive hardware featuring a 7 inch LCD touch screen and an EPS32 S3 microcontroller.
This video demonstrates its use: https://www.youtube.com/watch?v=y_Q7uNVt3vs
With the Decent espresso machine comes an Android tablet running a control software written in TCL. This software does multiple things:
- make espresso
- configure brew profiles
- configure steam, flush and the hot water dispenser.
For my every day coffee routine I only need the functionality of making espresso. The other functionalities as well as the fact that a whole stack of Android operating system and a TCL runtime needs to behave sometimes made it unnecessarily difficult to just make espresso.
Not so much for me - as I am a tech0146 nurd. For my wife and sons the standard operating environment seems to have an intimidating touch to it so that they won't use the machine. I wanted to find out if it is possible to create a controller hardware and software that makes using the machine fun for people that just want to make an espresso - given such people do exist.
I can imagine this simplified controller could also be interesting for people using the Decent espresso machine in a more professional environment.
!!Please note, that this is a hobby project I did for my personal education and enjoyment. It is not a commercial project!. There is no guarantee that it runs outside my house or without my hands on it. If you use it, use it on your own responsibility. I am not taking any responsibility for any harm it may cause to you or your equipment!!
My controller features a very opinionated and simple set of functions.
Turning on the machine, turns on the controller. It does not have a battery that does not like being charged all the time. It is powered by the machines power supply.
The controller runs a firmware written in C/C++. It runs directly on the hardware. No operating system that needs updates, or which the user sometimes suddenly falls into. No programming language runtime that might stall.
The controller talks to the machine and the scale via Bluetooth BLE. The connections is automatically made when any of the parts of the system becomes available. No user interaction is required.
The most interesting part of the Decent espresso machine is that it defines a file format for brew profiles. One profile can be uploaded to the machine at any time. The machine will execute the loaded profile when the user presses the brew button on the group head.
My Controller allows to copy as many profiles from the machines tablet to an sd card as the user decides. Once the sd card is inserted into the controller, the user can choose up to 5 profiles to be displayed in the UI as buttons that can be selected. Once tapped on a profile's button it gets uploaded to the machine.
I noticed that aside from the profile and the many parameters the machine allows to change I often adjust
- target espresso weight
- brew temperature
- steam flow
- flush time
These 4 parameters are available on the UI to change for each espresso brew.
While the espresso is being made the controller displays the current
- brew temperature
- water flow
- pressure
- weight
- brew time
in real time.
This data is displayed as changing numbers and as a graph over time. This is pretty much the same as in the standard Decent software.
The firmware runs on a device made by Waveshare called ESP32-S3-Touch-LCD-7. It is basically a 7 inch touch lcd with a pcb attached to its back. The pcb hosts among many other things
- the ESP32-S3 microcontroller
- the sd card slot
- an USB-C port to supply power
I wrote the firmware in written in C/C++. It is based on the ESP-IDF framework which is provided by Espressif, the company that makes the ESP32 microcontroller.