Scalable touchscreen controller from Microchip Technology provides configuration flexibility

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US-based Microchip Technology has announced its new maXTouch touchscreen controller, which it says enables automotive designers to satisfy various and unique aspect ratios for touch displays in cars. Its latest offering includes additional functional safety support requested by OEMs.

The controller can reconfigure its driving and receiving touch channels to match the exact screen format, from 1:1 to 5:1 aspect ratio, including the popular 8:3 automotive aspect ratio. This feature enables customers to efficiently use the number of touch channels available, without the need to select a larger, more expensive touch controller. Furthermore, the company notes that customers can save additional development and validation time and resources by reusing a common PCB design to support different touch sensor aspect ratios. These settings do not require firmware modification, leading to lower design risk and faster time to market.

“As touch displays have become more popular in automotive user interfaces, car manufacturers are using various display formats and shapes to accommodate their interior design and emphasize their brand identity,” said Clayton Pillion director of the human machine interface business unit at Microchip Technology. “As the number one automotive touchscreen controller supplier, we know that products with enhanced diagnostic features are a significant advantage to customers who are designing with unique features and increasing ISO 26262 functional safety requirements in mind.”

The controller also offers two communication interfaces operating simultaneously, which allow a bridgeless connection to the back channel of the LVDS video link for touch information and a connection to a local microcontroller (MCU). The bridgeless topology reduces touch latency to improve the user experience. It also guarantees full compatibility with the maXTouch software driver, available for all major automotive operating systems, including Linux, Android and QNX.

When connected with an appropriate local MCU, the second interface offers several functions. This includes a redundancy link to the head unit through a CAN bus or 10BASE-T1S automotive Ethernet link for increased functional safety at the system level. Furthermore, it provides local access and control of the maXTouch touchscreen controller’s features such as a capacitive keys report, live touch sensor diagnostics and raw data for external and custom post-processing. Finally, it has over-the-air and secure firmware update capability using Microchip’s TrustAnchor100 companion chip.

The MXT1296M1T also embeds various functional safety features to constantly check the integrity of the touch controller operation, as well as that of the connected touch sensors. The Failure Modes Effects and Diagnostic Analysis (FMEDA) and functional safety manual, dramatically ease the customer experience to design, build and certify a system for Automotive Safety Integrity Level B (ASIL-B) applications to the ISO 26262 standard.

The controller allows for high-resolution transmit waveform control to lower RF emissions and avoid interference with the car radio or RFID systems. With screen sizes increasing in cars, RF emissions generated by the projected capacitive touch technology are growing. Emission limits vary in amplitude, frequency and bandwidth for each major car manufacturer.

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Lawrence has been covering engineering subjects – with a focus on motorsport technology – since 2007 and has edited and contributed to a variety of international titles. Currently, he is responsible for content across UKI Media & Events' portfolio of websites while also writing for the company's print titles.

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