Building a vending machine is a process of integrating and combining several aspects of technology. Starting to build a cabinet for vending machine and designing coin and card payment method. This book does not explain to build a cabinet. Please try to look for information about building a cabinet for vending machine.

Technically, a vending machine is a finite state machine (FSM). The machine works under its states. Each state has been defined for input and output. A simple FSM for a vending machine can be described as follows:

Start with the Select Product state. It waits for input from the user. Once it is selected, the user can enter coins for the selected product. If the user cancels the transaction, the money will be refunded. If not, the system will validate the coins and compare it to the product price. If it's valid, the system will deliver the selected product.

In our implementation, we can use a Raspberry Pi as the central unit for the vending machine. The Raspberry Pi will control input from the user and handle product selection processing. It usually uses a motor, so we need relay modules to communicate with them.

The advantage of using a Raspberry Pi for vending machine implementation is to get the rich features it offers in computing and IoT capabilities. You can make a cluster of vending machines that can be controlled remotely.