Touch displays often require specialized touch controllers to drive displays, which can bump up the cost of final products. To mitigate cost increases, Microchip has just released a free touch library for use with most PIC, AVR, and SAM microcontrollers.

For some, it seems like only yesterday that touchscreens started to become integrated into products, taking up the mantle as our primary technology interface from the mouse and keyboard.

The first touch displays that I remember used resistive displays which could be found on the LG Optimus, Sony Ericsson, and even the Nintendo DS. But it was not long before capacitive displays took the market by storm and now the majority of displays are capacitive.

There are many reasons for the dominance of capacitive displays over resistive displays, including multitouch support, better screen contrast, and higher sensitivity. Now that displays can be found in many products and most mobile devices use touch screens, customers are beginning to expect such technology as standard. This expectation is pressuring designers to integrate touch displays into their products,

But a few issues come with this touch revolution. Integrating a touch display usually requires a touch controller which can increase the cost of manufacturing. And with the slowly rising popularity of wearable electronics, space on a PCB is becoming seriously precious.

In response to the rising demand for touch-oriented design resources, Microchip has released their 2D Touch Surface library that brings touch display capabilities to simple microcontrollers including PICs, AVRs, and SAMs.


Image courtesy of Microchip.


Microchip’s Touch Library

The library (which only requires ADC2 and 14KB free program memory) allows the designer to easily create phone-like UI elements without the need for a complex operating system in the background. This means that products such as the PIC16F1559 (costing as low as £0.90 per piece), can be used to create user-friendly interfaces without losing a tiny footprint.

The touch library also has other features, including:

  • Single/dual finger tracking
  • Dual finger surface gestures
  • Water-tolerant 2D touch sensing
  • Noise-robust touch sensing
  • Low-power touch (sleep scan mode consumes as little as 5uA)
  • Simple integration into Microchip projects
  • Library access and GUI based configuration via MCC / START


Gesture Control: The Next Interface Paradigm

But touch control is not the only capability of the Microchip touch library; with further processing, gestures can be detected, as well. This reflects the fact that gesture recognition is poised to become the next form of interaction to work with, and possibly overtake, touch interfaces. It was just about two years ago, remember, that Google's Project Soli introduced us to some novel gesture recognition concepts. These concepts, such as the pinch and zoom gestures, are now standard motions, also included in Microchip's product demonstration.

These gestures can be detected from up to 8 inches away from the display. The image below shows the different gestures that can be detected using the library.


Gestures built into the library. Image courtesy of Microchip


Another thing that the Microchip website features is the ability to match gestures to GPIO pins. While they do not go further into detail about this ability, this could mean one of two things (or both). The first possibility is that when a gesture is detected, it can send a signal to a GPIO pin which can be picked up by an ISR. This would result in lightning fast responses from complex gestures as the gestures are directly linked to the hardware.

The other possibility is that gestures could be used to output signals from GPIOs as soon as they are detected, which could be used to drive another microcontroller or I/O device. Either way, there is no operating system requiring overheads which results in faster responses from touch displays.



User interfaces are changing more rapidly than ever. The release of Microchip's library could allow many more designers, including students, to keep up with these trends and design better systems. If you decide to check out the library, please let us know your experiences in the comments below!