LND (on BTCPayServer)

This part of the guide will show you, how to connect your LND node on a BTCPayServer setup to your LightningATM.

Make sure, you have finished the hardware video part 3, before you attempt to setup your wallet (https://www.youtube.com/watch?v=A9JKUQvvmYM)

⚡ LND (on BTCPayServer)

⏫ Updating your current installation

Before you continue, make sure you are on the latest version of the ATM software. For this we go into the LightningATM folder and execute one git command:

cd ~/LightningATM
git pull
sudo pip3 install -r requirements.txt

You should now have the latest changes and therefore the latest version of the LightningATM software on your Raspberry Pi.

🤯 For a little more advanced users

The coming steps will involve a pretty automated process and the ATM literally configures itself. If you feel like you could take up a little challenge then stop reading and set it up yourself with the following hints of mine. If not, just skip this step and move down to Displaying your BTCPayServer QR code.

  • In your BTCPayServer go to SERVER SETTTINGS and then Services.

  • Go down to the table and where it says LND (REST server) and click See information

  • Go all the way down and where it says More details... click on "by clicking here"

  • What we need here is REST Uri and the Macaroon

In order for the ATM to connect with your LND node on BTCPayServer, REST Uri and the Macaroon will now have to be inserted into the configuration file of the ATM. The configuration file of your AT can be found here: ~/.lightningATM/config.ini

Let's inspect what is inside this file with the editor nano. Type in the following to open the file with the nano editor:

nano ~/.lightningATM/config.ini

Towards the end of the file you will find a section that's named [btcpay] and there is a variable url. Just below there is another section [lnd] with a variable macaroon.

You will now have to set those variables equal to the values that you've found in your BTCPayServer interface. Save the file, exit and restart your ATM. It's now configured with your LND node on your BTCPayServer! Congrats 🎉 , you can now skip the next steps and move all the way down to First transaction with the ATM

📱 Displaying your BTCPayServer QR code

Log into your BTCPayServer where you have your LND node running. In the menu choose the item SERVER SETTINGS and then Services. That's what this will look like, on a mobile phone:

At the bottom in the table you can see the column Access Type and in there LND (REST server). Next to LND (REST server) click on the link See information. Scroll down a little and find the green button that reads Show QR Code an click it.

This is all we need - have this QR ready for the next step. Be aware that this QR code is only valid for 10 minutes so you might need to refresh your browser and create a new one when you'll get an error at the ATM.

👩🔧 Connecting to the ATM

We will now connect the LND node to your ATM. For this we access our ATM again through SSH, change into the LightningATM directory and start the software with:

cd ~/LightningATM

It's best to monitor the log file with tmux, while you are doing this. Check out how to do that here:

Monitoring the log file

This will again start the ATM software and we get to see Welcome to the LightningATM on our screen.

We'll now have to put our ATM into the "credentials scanning" mode. This can be done by pushing the button 3 times.

After you pushed the button three times your display should say Please scan your wallet credentials. Now take your mobile phone with the LND BTCPayServer QR code and show it to the camera.

It will now scan your credentials, evaluate its content and safe it to the configuration file of the ATM. If you've been successful, your screen will say Success!! and your LND node is successfully linked with your ATM ⚡ .

🤑 First transaction with the ATM

Let's make a first proper transaction now!

Insert some coins into the coin acceptor of the ATM and see how the balance increases on the display (give the ATM some time between coins for coin recognition). When you've inserted enough, press the button once to start the payout process.

The ATM will now go into the "invoice scanning" mode and say Please scan your invoice and a short countdown will appear. Your ATM is now in an indefinite loop and will constantly scan for Lightning Invoices. If you want to stop it, you will have to press Ctrl + c to manually interrupt the process.

Now take another Lightning Wallet (people often use their mobile phone wallet) and create and Lightning Invoice. You have two options:

  1. Show a "zero satoshi" invoice.

    This is an invoice that does not request a specific amount of satoshis (some wallets let you do that).

  2. Create an invoice with the exact amount of satoshis.

    This is an invoice in which the mount of satoshis requested is encoded into the QR code (higher or lower value invoices will be rejected.)

Once the invoice has been scanned and was evaluated successfully, your LND node will try to pay it through the Lightning Network. If successful, both your mobile wallet and your ATM will confirm the transaction. Congratulations!! 😎

Join the Telegram group here: https://t.me/lightningatm_building

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