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IoT for vending: MDB Raspberry Pi HAT

The internet of things (IoT) is fast approaching and will affect every area of our lives. This will equally be true for the vending industry. That’s why we have created an MDB Raspberry Pi HAT.

While many vending machines these days are already connected to the internet, in cases this is still considered an “add-on”, or a telemetry unit. This means there is an old-school VMC (vending machine controller) that talks MDB. MDB is a 9 bit protocol (yes, you read correctly) designed around a bus where peripheral devices can be attached. It has strict and very short timing constraints. The internet add-on is then either attached to this bus or the the VMC.

MDB was clearly designed for hardware components that run some sort of low-level firmware that implements the protocol. It does not suit modern, state of the art software solutions. We made this discovery when we created our first MDB cashless peripheral. Soon we realized that we needed a piece of hardware that enables integration with MDB. You can read more about this experience here.

You may ask why MDB was not replaced decades ago? There are probably multiple reasons for this:

  1. Long investment cycles for vending machines.
  2. VMCs use firmware that cannot just be updated to something new. Someone has to go there to update the machine.
  3. There are many MDB peripheral devices available that might not offer any other interface. For example coin changers or bill validators. These are still crucial parts of a vending machine.

There are more modern vending machines out there today, but the vast majority will still use MDB.

Innovative Vending Machines

So how to create a more modern vending machine? After we created our first cashless peripheral, we released the MDB Converter 3, which takes care of the difficult parts of the MDB specification and provides a simple interface for modern devices (USB, serial and Low Voltage TTL). This is what we used back then in our cashless peripheral. On top of that we used some processor board and created our own hardware. This was before Raspberry Pi and Arduino. Today, we would of course do this using an MDB Raspberry Pi HAT, which we now have created.

We are proud to release this new product called MDB2Pi. It is an MDB Raspberry Pi HAT and some of its features are:

  • Can be used as MDB VMC or MDB cashless peripheral
  • Supports MDB Logging/Tracing
  • Has a Real Time Clock (RTC)
  • Powers the Raspberry Pi through the MDB bus
  • Provides a low level API to send and receive MDB messages. It does not alter the MDB payload, which gives you the full control over the MDB implementation.
  • We provide sample implementations of the API in C# (SDK)

This product will give you the power to create a modern vending machine, because you can delegate the old-school MDB stuff to the MDB2Pi, while you have state of the art options on your Raspberry Pi. Imagine you can update your VMC software remotely. Imagine you can turn features on and off remotely and much more. Without any other extra add-ons. I am sure you will have many and much better ideas than these…

You can find more details about the MDB2Pi here and the product is available here.

Martin Gloor

Martin is responsible for our Test Automation Product Department and Abrantix in the APAC region. He is a payment industry specialist with a high knowledge of the business and in-depth technical skills.

Comment by Zafar |


Where I can get the power pin out(6 pin details ).
Also I am trying to develop the basic software to interface the same with the coffee machine. Where I can get the manual for the same.
Please help.

Thank you.

Comment by admin |

Please send an Email to with your question.

Comment by Sugandha Sharma |

From where I can get this module?

Comment by HM |

I am using your abrantix mdb2pi raspberry pi hat to interface a raspberry pi and a Vendi credit card reader. We are unsure how we need to initialize the hat / really how we need to get started.

Do we just send a UART 8-bit packet to the hat and let the hat convert it to a 9-bit MDB packet?

Also, do we need to call any initialization code on the raspberry pi to let the hat work?

FYI, we are writing a custom C library to implement what we need to do.

Comment by Corvers Willy |

I’m looking for an interface between a Coca-cola vending machine and a normal open contact from a access control system.
Now i found on the web your intrface.
Can you tell me if this works with this type of fending machines.
What is the cost and delivery time for this.

Best Reagards Corvers Willy

Comment by admin |

Hello Willy, I think our MDB Converter or MDB2Pi will work for your use case. You can find prices and availability in our webshop: Best regards, Daniel

Comment by admin |

You can find everything in our web shop:

Comment by Martin Gloor |

You can find more information on the MDB2Pi configuration here:
In order to get this to work, you need to implement a proprietary protocol called Command Protocol in your C application. We provide an SDK with the documentation and some C# sample code here:
Best regards, Martin

Comment by Jesus Romero Espinoza |

I want to buy this hat, but im wondering if i buy a mdb Y cable will i be able to have a coin acceptor and a bill acceptor hooked up?

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