I recently googled a couple of raspberry pi implementations of a vending machine interface but none of them had the specifications I would need. Ideally, the cryptocurrency payment acceptor would integrate with the same module as the credit card reader and communicate with the industry standard MDB specification for vending machine payment systems. Also, low data usage is another factor. My machines currently use less than 5 MB per month for telemetry and credit card payments.
None of my machines are currently capable of displaying a QR codes, but some do have contactless credit card readers. The credit card payment system has the capability of using prepaid cards. I was wondering if an app could interface as a prepaid card for the purposes of the vending machine payment system so that no new hardware would be required. I'm not sure whether BlockPay could be used in this way, that is, to add credit to a virtual prepaid card on an NFC enabled phone?
I will send you an email to talk further.