Design Vending Contactless Payment Device

I’m upgrading a fleet of vending machines and need a full design for a compact contactless payment module that can drop straight into the standard MDB/Executive slot already present in each unit. The reader must process contactless bank cards (EMV), common mobile wallets (Apple Pay, Google Pay, Samsung Pay, etc.) and our own closed-loop prepaid vending cards, then return a simple “approved/declined” signal on the existing vending bus. The machine firmware will handle product release, so all you have to supply is reliable payment capture and a clear on-device approval indicator.

What I’m looking for
• Schematic, PCB layout and component BOM for the reader, antenna and controller.
• Embedded firmware (preferably in C/C++ or an RTOS you’re comfortable with) that handles card/wallet detection, secure transaction processing and basic prepaid-card balance checks.
• Simple API spec or command set showing how the module reports Approved/Declined over the standard connection.
• 3D enclosure design ready for injection-moulding, sized to mount in the space of a traditional coin mech.
• A brief test plan so I can validate contactless range, transaction speed and EMV compliance on site.

Acceptance criteria
1. Successfully processes contactless EMV card and NFC mobile wallet taps in under 2 s.
2. Accurately debits and logs closed-loop prepaid cards using your balance-tracking routine.
3. Returns Approved/Declined over MDB without blocking other peripherals.
4. Passes basic PCI-P2PE best-practice checklist (no sensitive data stored or sent in the clear).

Let me know which secure element, NFC controller or dev kits you’d base the design on and any certification experience you have so we can plan the path to production.