Touchscreen Controllers That Make Your Automotive Display Outperform Your Mobile Devices

Design of Modern Automotive Capacitive Touchscreens

To improve readability, usability and interior design, automobile manufacturers are increasing the size of the touchscreen displays they incorporate into their vehicles. These displays must meet strict standards relating to shock and vibration for equipment mounted in automobiles, meaning they require thicker cover lenses. In addition, gloved touches need to work safely (unlike in many mobile phones). These requirements and features can reduce the touch sensitivity of the human-machine interface (HMI) system. This issue is compounded by the fact that drivers have come to expect a similar touch experience from their automobile displays to that provided by their mobile devices. Another issue pertaining to the use of larger touchscreen displays is that they are more likely to interfere with other radio frequency systems in a vehicle (like AM radio or remote car access). These issues represent a major challenge to the design of modern automotive capacitive touchscreens.

maXTouch^® Technology Solution

To help overcome these challenges, Microchip has developed their maXTouch^® touchscreen controllers. These have been designed in line with current automotive industry trends of increased touchscreen size and reduced finger touch separation in automotive applications. This family of single chip maXTouch touchscreen controllers can provide consumers with the type of high-quality touchscreen user experience which they expect in vehicles. The latest maXTouch touchscreen controllers can detect touches through a front panel made of 10mm of glass (or 5mm plastic) for bare fingers operation or through 6mm glass (3mm plastic) for multitouch thick glove operation. Microchip's maXTouch touchscreen controller solutions also offer superior signal-to-noise capability to address the requirements of thick lenses and can even support multiple finger touch through thick gloves in the presence of moisture.

Maintaining High Levels of Functional Safety

Safety and reliability are critical in automotive systems and the ATMXT1296M1T-A supports these by incorporating self- and sensor-diagnostic functions. These features constantly monitor the integrity of the touch system and support the Automotive Safety Integrity Level (ASIL) classification index as defined by the ISO 26262 Functional Safety Specification for Passenger Vehicles. The controllers also feature technology that enables adaptive touch utilizing self-capacitance and mutual-capacitance measurements to detect all genuine touches while avoiding false touch detections. It also features Microchip’s proprietary signal shaping technology that significantly lowers emissions to help large touchscreens using maXTouch controllers meet CISPR-25 Level 5 requirements for electromagnetic interference in automobiles.

Microchip’s maXTouch touchscreen controller solutions provide full scalability by offering the industry’s only portfolio of automotive-qualified touchscreen controllers which enable the design of multiple platforms, from small touchpads to much larger displays (up to 40 inches), using the same development environment with the same host software interface providing a high-quality user experience. These resources reduce design time and reduce system and development costs and time to market.

Development Tools

Many of the parts in the maXTouch touchscreen controller family come with a companion evaluation kit. These kits include:

• PCB with the maXTouch touchscreen controller
• Touch sensor on a clear glass lens
• Flat printed circuit cable (FPC) to connect to the sensor display
• Converter bridge PCB (to connect the kit to the host computer)
• Software and documentation

All parts are also compatible with maXTouch Studio, a complete software development environment to support the evaluation of maXTouch touchscreen controllers. You can purchase one of the evaluation kits directly from Microchip or Microchip’s global distribution network.

For more information on Microchip’s automotive touch solutions, visit our Automotive Touch page.