Arduino controlled robot arm

I enjoy tinkering around with robots and electronics. Bridging the invisible world of software with the real world of physical things.

I discovered I could glue a breadboard to the side of the base of this robotic arm, and that I could hold the arduino board to the base with elastic bands. and that the adafruit motor board left 5 analog pins free to use, and that I could put a switch, a potentiometer and an hbridge in the breadboard with these five free pins. And that I could substitute the broken led with a new one with my soldering iron 😀

It is now all ready and working. Every time I hold down the switch button it activates one of the five motors iteratively. With the potentiometer I can have the motor run in one direction or the other. And the LED at the hand of the robot arm shines while the button is pressed.

The only problem pending is I need to change all the worn out gears from the motors as they are eroded from previous experiments (the problem with dc motors as opposed to servo motors is that you can’t know where they are, so I overextended them eroding the gears)

Machine Learning 101

I started self-training on machine learning. I bought a copy of “Hands-On Machine Learning with Scikit-Learn, Keras & Tensorflow” and am enjoying it a lot. I have a small moleskine with which I break down the concepts one day at a time 🙂

So far I have not yet encountered any concept which is not trivial. This means I am progressing. In my experience things are either trivial or impossible. Our job is to break down impossible tasks until they become trivial 🙂

Monkey Island

One of the things I cherish from my youth are the days when I would be immersed in Point and click adventure games: Lucasfilm’s Indiana Jones, Monkey Island or Loom, Sierra’s Kings’ Quest or Leisure Suit Larry…

If I won the lottery tomorrow I would retire to learn how to create these wonderful worlds, to immerse the players in my adventurous story 🙂

Yesterday I learnt how to set up scummvm in my retropie and load Monkey Island. I want to be a pirate! 😀

Setting up Lightning Network [3/3] – what to do with your lnd node?

Now that you have your node set up and you have established a few channels you can start routing payments. You can see my node here I have opened three channels for now, and with it I am able to route payments anywhere.

You can set up a account to receive tips in satoshis. It creates a custodial lighning wallet where people can send you tips. You can send me some satoshis at (as of today 1 satoshi equals 0.00003416 Euros, so don’t be shy, if you go wild and send 1,000 satoshis it will be 3 cents of a euro 😉 )

To send a tip to you need to use the payinvoice command, instead of the sendpayment command as you won’t have an invoice and you can send any amount you want.

lncli --lnddir /opt/lnd-data/ --no-macaroons  payinvoice --pay_req lnbc1pw8aa5app5t3zqgnsq2e80s47s33a4rqc4w3spvamwp5tch732zucgglcyefwqdph235hqurfdcs9ymm8v4kkzm3q9p6xjursd9hzumt99y582vfj8ycny2gcqzysxqyz5vqu05rc3mk3m5cteh8gsvh3pf696p4wfdeezq29kkxcdrwjmtj64njk5lj4nv4jul96jcsqvw94a57y4722lrzdygu87jfkw2leu9ceqqpqmmcgl --amt 100

On the testnet a very cool test to do is buy a Blockaccino at starbloqs, check out a video here

You can request others to send you money by sending them an invoice

lncli --lnddir /opt/lnd-data/ --no-macaroons addinvoice 100 --expiry 36000
        "r_hash": "f9ba7fd5b0be3d768c29aa951b4a215ea7e37133ebb41fd5a7d424e7981551de",
        "pay_req": "lnbc1u1pw8a7u6pp5lxa8l4dshc7hdrpf4223kj3pt6n7xufnaw6pl4d86sjw0xq4280qdqqcqzysxqypr9qfrglxdwv8jdc9xlsyatugwztdvsn89y4hmlm2mgds5wyl9k3c963uk66zhntp6940yxpfz5fa0au9mcg4c0sfc77eg589fmpnjhcs6gp49ghuh",
        "add_index": 1

Once you’ve created the invoice you can send the pay_req to the payer (in the above example lnbc1u1pw8a7u6pp5lxa8l4dshc7hdrpf4223kj3pt6n7xufnaw6pl4d86sjw0xq4280qdqqcqzysxqypr9qfrglxdwv8jdc9xlsyatugwztdvsn89y4hmlm2mgds5wyl9k3c963uk66zhntp6940yxpfz5fa0au9mcg4c0sfc77eg589fmpnjhcs6gp49ghuh)

Others can send you money with the sendpayment command by paying your invoice

lncli --lnddir /opt/lnd-data/ --no-macaroons sendpayment --pay_req=nbc1u1pw8a7u6pp5lxa8l4dshc7hdrpf4223kj3pt6n7xufnaw6pl4d86sjw0xq4280qdqqcqzysxqypr9qfrglxdwv8jdc9xlsyatugwztdvsn89y4hmlm2mgds5wyl9k3c963uk66zhntp6940yxpfz5fa0au9mcg4c0sfc77eg589fmpnjhcs6gp49ghuh

With your lightning network node you can send payments which are:

  • Borderless: The internet knows no boundaries, it has no borders, you can as seamlessly send payments within your country, your continent, your planet, or your solar system. In the future we may need to send money to mars!
  • Anonymous: Since payments are routed via a mesh of nodes which can’t see the whole end to end payment route, payments are anonymous. This is different to on-chain bitcoin payments, which are only pseudo-anonymous and can be tracked to you.
  • Instantaneous: Once you start playing with lnd you will see that it takes less than a second to route a payment. This is mindblowing if you think about it. Internet packets are being communicated throughout the planet, from one internet provider to another, from one router to another, from one lnd node to another, until they reach their destination.
  • Low cost: The nodes (yours as well) set the fees they want to charge to route payments. The route chosen is always the cheapest one so this incentivises nodes to reduce the fees. Sending payments over the lightning network costs cents of euro equivalent in satoshis.
  • World scale: Lightning is capable of millions to billions of transactions per second across the network. Visa, which is currently the benchmark can transfer less than 2,000 transactions per second.

One problem lightning network has is that you can only send or receive as much money as you have route bandwidth for, this means that if you want to be able to receive payments worth 500 Euro, you need to have channels open worth 500 Euro. This can be pretty expensive for high value payments. Due to this constraint the lightning network can work very well for low value payments, like buying a coffee, and not so well for high value payments like buying a house. In any case high value payments can be done directly using the bitcoin blockchain without using the lightning network layer and are usually not done in high volumes. (Maybe a third layer protocol could be used to spit large payments into groups of smaller ones similarly how tcp over ip is capable of splitting large packets of information into smaller ones and guarantee order and completeness, you could split a payment of 1000 satoshis into two payments of 500)

This is the future of how robots will pay each other.

Setting up Lightning Network [2/3] – Set up your lnd node

Once you have set up your bitcoin node you can start setting up your lightning node. We will install lnd.

lnd is written in go. First we install the go compiler.

mkdir -p $HOME/src
cd $HOME/src
git clone
cd go
git checkout go1.12
cd src

add the following to your $HOME/.bashrc
export $GOPATH=$HOME/go
export PATH=$PATH:$GOPATH/bin/:$HOME/src/go/bin

. $HOME/.bashrc

Once go is working we install lnd

go get -d
cd $GOPATH/src/
make && make install
make check

In order for lnd to communicate with your bitcoind process you need to configure zmq in your bitcoin.conf (if you followed my previous post you will have compiled bitcoind with zmq support).

cat >>/opt/bitcoin-data/bitcoin.conf

Create a directory and config file for lnd

mkdir -p /opt/lnd-data/
cp $HOME/go/src/ /opt/lnd-data/lnd.conf

These are some important variables to set up in your lnd.conf

[Application Options]

Start your bitcoind and lnd nodes.

bitcoind --datadir=/opt/bitcoin-data/ -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A=
lnd --configfile=/opt/lnd-data/lnd.conf

Now that your lnd node is running you need to create a wallet. It will ask you for a wallet password and a seed mnemonic passphrase. Write these down on paper and keep that paper safe.

 lncli --lnddir /opt/lnd-data/ --no-macaroons create

Create a new address so you can send some bitcoin to your lnd wallet

lncli --lnddir /disco-dos/lnd-data-mainnet/ --no-macaroons newaddress np2wkh
    "address": "3HUMZ7NVBQQqNHSnnj7dwS929YBUHTQoqu"

now send some satoshis (1 satoshi=1/100.000.000 btc, as of now 1 satoshi=0.00003 Euro) to your lnd wallet

bitcoin-cli -datadir=/opt/bitcoin-data -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A= sendtoaddress 3HUMZ7NVBQQqNHSnnj7dwS929YBUHTQoqu 0.001

if you are on testnet you can get some free satoshis (a.k.a. sats) by googling lightning network testnet faucet (here’s one). Once you have sent some money to your lnd wallet you can check your balance.

lncli --lnddir /opt/lnd-data/ --no-macaroons wallletbalance
    "total_balance": "242539",
    "confirmed_balance": "242539",
    "unconfirmed_balance": "0"

lighning network is a mesh of point to point nodes, so let’s connect to some nodes in the network. You can find nodes to connect to here for mainnet and for testnet.

For example, let’s connect to 0232e20e7b68b9b673fb25f48322b151a93186bffe4550045040673797ceca43cf@

lncli --lnddir /opt/lnd-data/ --no-macaroons connect 0232e20e7b68b9b673fb25f48322b151a93186bffe4550045040673797ceca43cf@

We can check all the peers we are connected to

lncli --lnddir /opt/lnd-data/ --no-macaroons listpeers

let’s open a channel for 100000 sats

lncli --lnddir /opt/lnd-data/ --no-macaroons openchannel 0232e20e7b68b9b673fb25f48322b151a93186bffe4550045040673797ceca43cf 100000

now we can route payments through this node to any node in the lightning network. For example if you live in USA you can order a dominoes pizza. Let’s draw in my twitter handle (@Rogeman) (all-in cost 7675 sats, or 0,25 Euro. Totally worth it! :D)

lncli --lnddir /opt/lnd-data/ --no-macaroons sendpayment --pay_req=lnbc75970n1pw8s4uzpp5gl4mvj9mcnyz4ehvjhnceyxvdecn60gjny95qq02wd80rj5eywdsdzy2pshjmt9de6zqen0wgsrwdfexus8q6tcv4k8xgrpwss8xct5daeks6tn9ecxcctrv5hqxqzjccqp2rzjqtkru466qeqlcsvm0ql5338v8geseqxa6x9kcnkqcef6p7msfhmw6zrut5qqpjsqqyqqqqlgqqqqqeqqjq5f54fkcjjspqc4j403l067q3ujcet6lvzm98jyqwkujzz43gufyq8cxumdrsrqxlkrrrpv2yj3ejn2syqwyx2jzfmz5ls0ym87sny7gpuvsj4l
Description: Payment for 7597 pixels at
Amount (in satoshis): 7597
Destination: 024655b768ef40951b20053a5c4b951606d4d86085d51238f2c67c7dec29c792ca
Confirm payment (yes/no): yes
        "payment_error": "",
        "payment_preimage": "cfc4a1f1974aeb3be9f7c29fc03d85757fe9f3f675ee2fd93d5b3a2b01fb5a97",
        "payment_route": {
                "total_time_lock": 565405,
                "total_fees": 78,
                "total_amt": 7675,
                "hops": [
                                "chan_id": 621324125340041216,
                                "chan_capacity": 100000,
                                "amt_to_forward": 7598,
                                "fee": 76,
                                "expiry": 565391,
                                "amt_to_forward_msat": 7598196,
                                "fee_msat": 76981,
                                "pub_key": "0232e20e7b68b9b673fb25f48322b151a93186bffe4550045040673797ceca43cf"
                                "chan_id": 606036515588079617,
                                "chan_capacity": 1259649,
                                "amt_to_forward": 7598,
                                "expiry": 565247,
                                "amt_to_forward_msat": 7598007,
                                "fee_msat": 189,
                                "pub_key": "0395033b252c6f40e3756984162d68174e2bd8060a129c0d3462a9370471c6d28f"
                                "chan_id": 621250457985744896,
                                "chan_capacity": 40000,
                                "amt_to_forward": 7597,
                                "fee": 1,
                                "expiry": 565103,
                                "amt_to_forward_msat": 7597000,
                                "fee_msat": 1007,
                                "pub_key": "0371513dee8725b7c4eae15c7a350e6559c5aa9c007d7d27ea436571acf6927e75"
                                "chan_id": 621254856070397952,
                                "chan_capacity": 500000,
                                "amt_to_forward": 7597,
                                "expiry": 565103,
                                "amt_to_forward_msat": 7597000,
                                "pub_key": "024655b768ef40951b20053a5c4b951606d4d86085d51238f2c67c7dec29c792ca"
                "total_fees_msat": 78177,
                "total_amt_msat": 7675177

Setting up lightning network [1/3] – Set up your bitcoind node

Lightning network is a Layer 2 protocol that sits on top of the bitcoin/litecoin blockchain. It enables instant, low cost, anonymous payments by routing payments through point to point channels in a similar way to what the correspondent banking system uses today to transfer fiat currency.

You can check out the map of channels of the lightning network at as of today, there are 3488 nodes

In order to set up your lightning network node, first you need to set up your bitcoin node. Here you have simple instructions to set it up by compiling it from source.

First we clone the git repository for the bitcoin core node

sudo apt-get install git
mkdir $HOME/src
cd $HOME/src
git clone

you will need libzmq3 in order for the lighning node to communicate with your bitcoin node, so we need to install libzmq3-dev

sudo apt install libzmq3-dev

now we configure and install the node

cd bitcoin
sudo make install

bitcoind is installed! 🙂 now we need to create a config file and create an rpc user and password so you can communicate with your bicoind node

./share/rpcauth/ roge
#This command will give you the user and password you will need to include in your bitcoin.conf
String to be appended to bitcoin.conf:
Your password:

Let’s create a directory where all bitcoin data will be stored. Be warned that this directory will hold a copy of the whole bitcoin blockchain which is as of today 243 GB.

We will copy a bitcoin.conf file to the bitcoin data folder

mkdir /opt/bitcoin-data/
cp $HOME/src/bitcoin/share/examples/bitcoin.conf /opt/bitcoin-data/

now we edit the bitcoin.conf file, the following variables are important

vi /opt/bitcoin-data/bitcoin.conf
#set testnet to 1 if you'd like to run a node for testing purposes not using real bitcoins.
#set daemon=1 to launch bitcoind as a daemon running in the background
#set rpcauth to the rpcuser you created earlier

We are set. Now we can start our bitcoind node with the following command. It could take one or two days to synchronise with the bitcoin blockchain.

 bitcoind --datadir=/opt/bitcoin-data/ -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A=

you can monitor progress looking at debug.log

tail -333f /opt/bitcoin-data/debug.log

you can connect to your bitcoind node using bitcoin-cli which allows you to manage your node

 watch bitcoin-cli -datadir=/opt/bitcoin-data/ -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A= getblockchaininfo

Now encrypt your wallet don’t forget this password. Write it down on a piece of paper and store that paper somewhere safe.

bitcoin-cli -datadir=/opt/bitcoin-data -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A= -stdin encryptwallet

now you can get an address where to deposit bitcoin in (you can buy these bitcoins in exchange for fiat currencies such as Euros or Dollars in exchanges like or do not send real bitcoin to a testnet wallet, they will be lost. You can get free testnet bitcoins by googling testnet bitcoin faucet. Here’s one (link)

bitcoin-cli -datadir=/opt/bitcoin-data -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A= getnewaddress
#This will return the new address where you can send bitcoin to
# the command will return something like 3NUvF2fvitxrU1fY43rCQivx9RtCgvXuEb

Once you have transferred bitcoins to your wallet you can see your balance

bitcoin-cli -datadir=/opt/bitcoin-data -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A= getbalance
#This command will output your bitcoin balance

In order to transfer bitcoins to another address you first need to unlock your wallet for x seconds

bitcoin-cli -datadir=/opt/bitcoin-data -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A= -stdinn walletpassphrase

Now you can transfer bitcoin to another wallet

bitcoin-cli -datadir=/opt/bitcoin-data -rpcuser=roge -rpcpassword=34ZofsEbG95rWITDv8w03crrzIYBioGAKfMqDq1yY1A= sendtoaddress enterthedestinationaddress entertheamounttotransfer

You can find all the bitcoin-cli commands here:

Now that our bitcoin node is ready, let’s set up our lightning network node! 🙂