Trill, Touch Sensing for Makers
It was Chris Anderson that originally coined the phrase “the peace dividend of the smartphone war” arguing that “…when giants battle, we all win,” and it’s that smartphone war that has brought us cheap sensors—accelerometers, gyroscopes, microphones, pressure and humidity sensors—as well as cheap screens and processors. It also made capacitance touch sensors available, with perhaps the most famous being the Makey Makey which raised on Kickstarter all the way back in 2012, or Bare Conductive‘s Touch Board which was funded a couple of years later in 2014.
Now there’s another touch sensor on the block—brought to you by the people that brought you the Bela, and the Bela Mini—they’re called Trill, and the folks are Belo.io are currently raising on Kickstarter.
The new Trill sensors come in three versions; the Trill Bar, a slider that can sense up to five touch points, the Trill Square, a touch pad that senses two axes of movement, and finally the Trill Craft, a 30-channel breakout board that lets you make your own touch interfaces out of anything conductive.
A lot of the capacitance touch sensors breakouts available to makers right now are based on the Freescale MPR121. However, the Trill sensors have been built around the Cypress CY8C20636A. This capacitance touch controller has more channels, with 33 compared to the MPR121’s 12, enabling you to create more sensitive sliders or high-resolution interfaces. Although the Trill sensors expose only 30 of these channels, as the others are occupied with I2C.
The Trill Bar is 101×22 mm and is a single axis sensor with a resolution of <0.1mm, allowing detection of up to five touches simultaneously, while the Trill Square is 69 × 69 mm two-axis sensor. Both sensors can be read every 5ms (that’s 200Hz), and while the sensors cannot detect the amount of pressure in a touch, they can detect the area of the touch. As touching lightly with your finger will normally mean a smaller area of contact between your finger and the sensor, while conversely heavier touches will generally have a larger area of contact, the effect is similar and the sensitivity of the sensors can be easily adjusted on the fly.
All of the Trill sensor boards use I2C to connect to a microcontroller board, with library support provided for the Bela and Arduino boards, along with support for Linux, in the project’s GitHub repo. The I2C address of the each sensor can be changed via the solder pads on the back, which allows you to use multiple Trill sensor with the same microcontroller, and chain up to eight Trill sensors of the same type together on the same I2C bus.
Both the Trill hardware and firmware will be released under a CC-BY-NC-SA license, so the design will be free for non-commercial usage, although right now the project’s GitHub repo has only library and example code. I’d expect the design files and firmware to be released either when the Kickstarter closes, or when the Trill sensors ship next year.
The Trill touch sensors are now funding on Kickstarter, with a single sensor—the bar, square, or craft—costing £12 (that’s around $15) at the early bird rate plus an additional £2 for shipping inside the United Kingdom, or £4 for shipping to the rest of the world, rising to £14 when the 30 early bird backer spots are gone. If you want to pick up a pack containing all three of the sensors, you can do that for £36 (that’s around $45) plus an additional £3 for shipping inside the United Kingdom, or £5 for shipping to the rest of the world. All of the rewards have an estimated shipping date of February next year, although of course with a Kickstarter, that’s always going to be subject to slippage.
