Dedicated controllers offer ‘no software’ to add touch controls

December 11, 2015 // By Graham Prophet
Silicon Labs’s TouchXpress fixed-function controllers claim to offer the fastest and easiest way to add low-power capacitive touch interfaces to embedded designs.

The CPT007B and CPT112S TouchXpress controllers eliminate firmware development, providing a simple turnkey solution for adding touch-based user interface designs to a wide range of products including home appliances, white goods, consumer electronics, lighting control, medical equipment and instrument/control panels. TouchXpress evaluation boards and advanced configuration and profiling software tools available within the Silicon Labs’ Simplicity Studio environment enable embedded developers to get their capacitive touch applications up and running.

The two TouchXpress family members in this release are:

• The CPT007B GPIO switch replacement device that enables developers to replace up to seven mechanical buttons with capacitive touch sensors with no firmware development. The GPIO interfaces provide direct on/off sensor status to the host processor.

• The CPT112S capacitive sense I ²C device features up to 12 sensor inputs to simplify the addition of capacitive sense functionality for touch-based interfaces. The I ²C interface provides an easy way to track the status of touch sensors, and an interrupt pin can wake the host processor from sleep after a proximity touch detection.

Both capacitive touch controllers support features such as moisture immunity, wake-on proximity, touch time-out, mutually exclusive touch qualifier and buzzer feedback for an enhanced user experience. The CPT112S device also offers a slider control option.

The controllers provide drop-in solutions that ease touch interface development for embedded designers of all skill levels. No firmware development, programming or capacitive sense expertise is needed to implement capacitive touch interfaces. No external components are required, and developers can configure and evaluate all capacitive sense parameters using Silicon Labs’ intuitive GUI-based Xpress Configurator and Capacitive Sense Profiler.

Energy efficiency enables long battery life, as well as the use of smaller batteries for wearables and other portable devices. High signal-to-noise ratio (SNR) results in better reliability and touch performance, which are important to instrumentation and control applications.

Features include;

  • ultra-low power: active current down to 200 µA with <1 µA sleep