Pepsi Fountain Drink Dispenser Touch Panel for ADA

USB Capacitive Touch - ADA Touch Interface


Project Description

Cornelius, the world leading supplier of beverage dispensing and cooling equipment was working with PepsiCo, a global food and beverage company to create a new modern drink dispensing machine that can be used in fast food centers and restaurants.

The machines used in fast food centers are generally self-serve in nature. Such machines should therefore confirm to American Disabilities Act (ADA). According to this act all new restrictions were placed on store counter height, width and maximum equipment height etc. to make it easy for people on wheel chairs to serve their own drinks. Please see drawing with dimensions below.

ADA Keypad Height

To meet the requirements of this law, Cornelius wanted a capacitive touch ADA keypad for their drink dispensing machine. Their drink dispensing machine already had a microprocessor based system running windows operating system. So, we suggested that we could build a capacitive touch system that could communicate button press and release information via USB just like a regular USB HID keyboard.

One of the challenges while developing this keyboard was that the overlay was going to be icons pad printed on an injection molded plastic. However, this was not going to be available to us during the keypad prototyping stage. So, we used our in house FDM machine to 3d print the overlay using ABS plastic and configured our keypad to work with this thickness.

This keypad was then subjected to beta testing by the client in a few locations. During the testing, it was observed that in high traffic regions, it is possible the button may get triggered when soda/water accumulates over a period of time along the wedges. Also, it was noted that buttons may get triggered if an employee were to wipe such panels with cloth.

To deal with these challenges, 2 features were added to our capacitive touch system. One was a 30s press time out. A button press is valid for a period of 30-35s. After this time the reference Value associated with this button is reset so that the press is rejected. The second was multi button press rejection. The panel will send a button press when one of the buttons is pressed. If multiple buttons are pressed, then a key release code is sent to the host computer via USB using the HID protocol.

A useful feature of our fast touch system is that they come loaded with a boot loader. In normal circumstances, the device will run its application code. This is also known as the run mode. A sequence of operations can be performed by the client in this mode to make the device enter boot mode. In the boot mode, a new program can be downloaded using a simple GUI application provided by us. In this project the 2 features mentioned earlier were added to the prototype devices and the client was able to continue testing.

We are happy to inform that this product is now in production.

As you can see capacitive touch interface design and manufacture is not an easy task. We have the expertise, tools and experience to guide you through it.


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