What we do



Contact details

telephone : 01285 582998

email :

Vending motor control

VMC (Vending Motor Control) is a board to control the internal operations of a vending machine. We developed a VMC board to control 24V motors to vend product. The board is effectively in two halves - one processor to drive the selected motor channel and a second processor to drive lamps and to accept commands from the vending machine control software. The two processors communicate using SPI, with the second processor designated as the master.

This design approach was important. It allowed us to separate out functionality, providing a dedicated controller for running the motor and monitoring its operation. This was a simple processor, so there was no additional cost to the approach but it provided a better partitioning of the work. The master processor handles the rest of the hardware in the vending machine, providing feedback through LEDs, monitoring delivery of the product and communicating with the vending machine control software.

The vending machine control software provides the user interface and the credit card payment scheme. It decides when payment has been accepted and which motor needs to be activated. The command is passed over a USB interface to the VMC and the motor control processor starts and monitors the motor until delivery is complete.

The two processors were part of the AVR family from Atmel and were programmed in C. We designed the hardware and wrote the firmware to control both processors.

Duty free control

We developed a different VMC board for a different application. Duty free shops in Ireland changed over last summer to stop advertising cigarette cartons to duty-free customers. In conjunction with Nuttalls and K6 Design Group, we designed a VMC board to control up to eleven motors to vend cartons from a bespoke machine designed by K6. Again, this used an AVR micro-controller and the software as developed in C. The board can drive and monitor up to 4 motors simultaneously and is able to detect a blockage so as to reverse the motor away from damage.

The motors are linear actuators with override switches at the end of the travel. In the software, we provided extensive diagnostic capabilities, using a couple of LEDs per channel to provide status information at the different stages of the delivery process. During startup, the board auto-configures, detecting which channels have motors connected, allowing for flexibility during installation.

Sorry the pictures are a little dull! It's hard to find an exciting picture of electronics hardware. Basically, boards are green and covered in components.