Bitcoin Forum

Are there any real world usage example of POS machine that capture crypto-currency's address QR code.

If there is, what is usage scenario of POS?

How to make (or develop) it?

POS machines connect to a centralised backend (usually bank clearing)
Cryptocurrencies are the exact opposite of that.

The only thing similar is payment processors like Coinbase or Bitpay, which is already what most merchants use.

You'll scan a QR code, and send bitcoins to that address for your purchase, and in the backend, either the bitcoins go directly to the merchant's address, or through the payment processor and they get settled in fiat.

So when normal store decide to receive bitcoin, he need POS machine? Maybe not? He just shows his printed static QR code image of his bitcoin address to customer?

Then customer uses his smart phone and photo it, then customer also need some kind of mobile wallet?

Exactly. QR code with the wallet address (or with address and payment amount, if it's fixed one) is displayed in the store, customer scans it with his mobile wallet and pays.

My point exactly; you don't need a POS machine because you're dealing with cryptocurrencies.

Exactly, yes.
All the customer need is a crypto wallet.
All mobile wallets support QR codes so you just need to scan the QR code.

But are there no ways of store can also provide/include specific BTC amount as well with store's address QR code?

Or store should make customer know how much BTC they need to pay?

Yes, the stores can store the amount of btc for a specific piece of item and this can be done by coinbox I think so, but sadly it has been abandoned. You can even try bitpay or similar other software. Not so sure about it, but it can be done and people can pay for the item by scanning the code.

You can include the amount you want the customer to pay and the purpose for payment also (payment label).
It's all defined in the URI scheme in BIP 21 (https://en.bitcoin.it/wiki/BIP_0021)

But when we're dealing with the mainstream and micropayments brought by 3rd-party (centralized) wallets, a POS Machine is a must for ease-of-access.

There's a way but the counter won't wait for at least one confirmation which is at least 10 minutes in situations like grocery payments or coffee shop orders.
So, it's not convenient to use Bitcoins directly for POS machine transactions.

You need to process the transactions off-chain like exchanges do.
with this, the users must trust your wallet/service like BitPay/coins does.

Usually an unconfirmed transaction will show in a matter of minute or two. Or you can use other coins with 1 minute block time :)