21UP

The new 21UP vending machine displays a Bolt11 invoice on the e-ink display when a button on the machine is pressed. When the invoice is paid it dispenses the requested can.

Currently being implemented:

• Create a spreadsheet of items sold, their price and time it took to pay the invoice
• Log the past screens as they were shown

To be implemented:

• Keep listening for the button even when an invoice is currently pending.
• Cancel the current invoice when a button is pressed
• Make use of LCD screen

Bugs:

• Occasionally the device would pick up a tray as full when it isnt

Prerequisites:

This guide and the code are optimized for Rasperry Pi OS (Bookworm).

Enable the SPI interface:

sudo raspi-config

Then select Interfacing Options -> SPI -> Yes to enable the SPI interface

Installation:

git clone https://github.com/Liongrass/21UP.git

cd 21UP

python -m venv env

source env/bin/activate

pip install -r requirements.txt

DHT11 Barometer

To install and configure the DHT11 barometer, some extra configuration is necessary.

First, edit the firmware configuration:

sudo nano /boot/firmware/config.txt

At the very end, amend the following line. Don't forget to replace the GPIO with your own:

dtoverlay=dht11,gpiopin=4

Finally, reboot the device to activate the changes.

More information can be found in DHT11.md

Run 21UP:

To run the machine, first copy the example configuration file.

cp .env.example .env

Most importantly, a valid LNbits URL and invoice key need to be set. Variables pre-fixed with a # sign have defaults and do not need to be set.

nano .env

Run the machine:

python main.py

Deploying as a service

To make the code run on startup and restart after a crash, we are using the PM2 utility.

Install PM2

Prerequisites:

sudo apt install git make build-essential

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh | bash

\. "$HOME/.nvm/nvm.sh"

nvm install 24

npm install -g pm2

Persist 21UP

pm2 start /home/user/21UP/main.py --interpreter /home/user/21UP/env/bin/python --name 21UP --exp-backoff-restart-delay=100

pm2 startup

This will give you a short command. Execute it to make 21UP run on startup.

Useful commands:

pm2 logs 21UP
pm2 list
pm2 monit
pm2 restart 21UP

Further documentation

E-ink display user manual

E-ink display circuit schema

Display Guide

Pin Inventory