The MIKROE-2474 TouchKey 2 click from MikroElektronika has four capacitive touch pads powered by Microchip's ATtiny817 microcontroller. This board also has an integrated Microchip QTouch controller. The click is designed to run on a 3.3 V power supply. The four LEDs onboard the click indicate when the key (pad) is pressed.  TouchKey 2 click communicates with the target microcontroller over UART interface or via serial peripheral interface (SPI). The TouchKey 2 click can be used in several different rugged environments and will be resistant to moisture and water droplets that fall on it. The plastic overlay on the TouchKey 2 click protects the board from moisture. Thanks to this feature the electronic components are safe. The ATtiny817 has a driven shield for improved moisture and noise handling performance. Capacitive buttons can be toggled even when placed under a layer of glass or paper. There are four LEDs for four touch keys. If key A is pressed LED_A is ON, etc. In addition, there is UART communication between ATtiny817 and main MCU.

Microchip's ATtiny817 is a microcontroller that uses an 8-bit AVR^® processor with hardware multiplier, running at up to 20 MHz and with up to 8 KB Flash, 512 bytes of SRAM, and 128 bytes of EEPROM. ATtiny817 uses the latest technologies from Microchip with a flexible and low power architecture including Event System and Sleep-Walking, accurate analog features, and advanced peripherals. Capacitive touch interfaces with proximity sensing and driven shield are supported with the integrated QTouch peripheral touch controller. The module supports wake-up on touch from power-save sleep mode.

TouchKey 2 Example Code
TouchKey 2 Schematic v100