Touchscreen controller delivers format flexibility for automotive displays

Microchip Technology Inc. has released a new maXTouch touchscreen controller that allows designers to meet a variety of aspect ratios for touch displays in cars. The MXT1296M1T also includes additional functional safety support to meet increased OEM requirements.

The MXT1296M1T 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, said Microchip. “This feature enables the customer to efficiently use the number of touch channels available, without the need to select a larger, more expensive touch controller.”

Touchscreen controller delivers format flexibility for automotive displays

MXT1296M1T touchscreen controller for automotive displays. Click for a larger image. (Source: Microchip Technology)

An additional benefit is that it allows designers to reuse a common PCB design to support different touch sensor aspect ratio, reducing development and validation time.

The MXT1296M1T is reportedly an industry first to enable the sensor channel reconfiguration by parameters. These settings also do not require firmware modification, resulting in lower design risk and faster time to market, according to Microchip.

The maXTouch touchscreen controller also provides two communication interfaces operating simultaneously. This allows for a bridgeless connection to the back channel of the LVDS video link for touch information and a connection to a local microcontroller (MCU), reducing  touch latency to improve the user experience while it guarantees full compatibility with the maXTouch software driver, available for all major automotive operating systems, including Linux, Android and QNX, said Microchip.

When connected to an appropriate local MCU, the second interface offers several functions including 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. It also 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, and over-the-air and secure firmware update capability using Microchip’s TrustAnchor100 companion chip

Touchscreen controller delivers format flexibility for automotive displays

MXT1296M1T solution example. Click here for the interactive version. (Source: Microchip Technology)

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

In addition, the MXT1296M1T allows for high resolution transmit waveform control to lower RF emissions and avoid interference with the car radio or RFID systems, particularly as RF emissions generated by projected capacitive touch technology grows along with increases in screen sizes, said Microchip.

The MXT1296M1T uses a dedicated on-chip 64-level digital-to-analog converter (DAC) to accurately shape the waveform of the transmitting lines, which “allows designers to precisely control the frequency response and optimize the harmonic emissions to meet specific OEM defined limits,” said Microchip.

The MXT1296M1T is available in volume production. The ISO 26262 FMEDA and Functional Safety Manual will be available for purchase the first quarter of 2022. Configuration and tuning is supported by the latest release of the maXTouch Studio Integrated Development Environment (IDE).

Two development kits are available to order now. The ATEVK-MXT1296M1T-A, an evaluation kit including development board with an USB bridge, 12.3”/ 8:3 format /1.1-mm One Glass Solution (OGS) touch panel, and touch key add-on boards for mutual and self-capacitance, and the ATMXT1296M1T-I2C-PCB development board for connection to a customer’s touch sensor.

Earlier this year, Microchip introduced the maXTouch MXT2912TD-UW touchscreen controller for automotive applications where the vehicle’s cluster, center stack, and co-driver displays are consolidated into wide screens up to 45 inches.

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