For code testing purposes, I used a battery.

To power the ESP32 I used a small 230VAC to 5VDC 5W (mobile phone 1A) charger and connected the ESP32 via micro USB.

I assembled the machine by putting back again the side plastic lids. I attached them by screwing the bolts back on the bottom of the machine. I inserted the pressure manifold and attached it back by screwing the 2 bolts. Finally I attached the front cap by screwing the 2 bolts.

Setup espressif toolchain on your computer:

Follow the official tutorial according your host OS in:

• Windows Setup Guide
• Mac OS Setup Guide
• Linux Setup Guide

In my case I used Linux, so if you’re also using Linux just use this shortcut:

sudo apt-get install gcc git wget make libncurses-dev flex bison gperf python python-serial 

Download the toolchain: In my case, Linux x64 bits

If you're using the terminal, cd into your Download folder and do:

wget https://dl.espressif.com/dl/xtensa-esp32-elf-linux64-1.22.0-80-g6c4433a-5.2.0.tar.gz

If you want to download using the browser click here.

Next, do the following:

mkdir -p ~/esp
cd ~/esp
tar -xzf ~/Downloads/xtensa-esp32-elf-linux64-1.22.0-80-g6c4433a-5.2.0.tar.gz
git clone --recursive https://github.com/espressif/esp-idf.git

Inside the folder esp you have just created, you should end up with two folders inside:

• xtensa-esp32-elf
• esp-idf

Define the above environment variables:

export PATH="$PATH:$HOME/esp/xtensa-esp32-elf/bin"
export IDF_PATH=$HOME/esp/esp-idf

You are now ready to cross-compile and flash your ESP32 device.

To create the coffee machine project, I used the hype framework.

This framework requires registration but it's free of use for a month.

After you register / login you can create a new app and select “Download Template” in this case for the ESP32

Download the template and decompress it to your project folder.

You will end up with something like this:

Except the file README.txt, as this was a file I wrote to explain how you can do to only download the libraries and not the template. The template already as your app identifier and access token hardcoded.

Now you can go to my dropbox repo and download the project.

Replace the files with your files in your project.

Inside your project, edit the file main/template.c

Between lines 24 and 36:

You have to replace the text between the quotes, for your wireless router name and respective password.

/* WiFi Settings */
/* Replace your WiFi Network Name for the "YOUR WIFI SSID" and respective password */
#define EXAMPLE_WIFI_SSID "YOUR WIFI SSID"
#define EXAMPLE_WIFI_PASS "YOUR WIFI PASSWORD" 

If you already created the app in the You have to go to "My Apps" and "Create new App".

After creating the new App, click on it and go to "Settings".

Now copy paste your App Identifier and your Access Token into the Source code.

/* Hype Settings */
/* Please read the README.txt file first.
   Here you have to set your App Identifier and Access Token given on the website */
#define APP_IDENTIFIER "YOUR APP IDENTIFIER"
#define TOKEN "YOUR ACCESS TOKEN"

 
Now in my case I defined PIN 23 to control my coffee machine push button, but you can choose any other output PIN.

/* Define here the GPIO Pin that you want to use to activate the coffee machine button */
#define MACHINE_GPIO 23

Save the file modifications and close it.

Run on your linux terminal:

make 

Make sure you have write privileges to flash your device. You can add this privileges either by:

• Adding your user to the dialout group (re-login is needed).

sudo usermod -a -G dialout $USER

•  Or by setting all privileges on the fly. (Where ttyUSBx is your device and “x” is its number, i.e. ttyUSB0)

sudo chmod 777 /dev/ttyUSBx

Finally I flash the device with the command:

make flash

 After all this is done you should have your smart coffee machine fully functional.