Atmel has announced an active stylus chip that delivers "accuracy and linearity of +/-0.25mm" on a capacitive touch screen from a 1mm diameter stylus tip, claimed the firm.
The chip is installed in the stylus and works with touch screens using any of the firm's maXTouch E series touch controllers.
Devices with suitable screens require only a software update and no hardware changes.
"We support passive conductive styluses already," Atmel marketing manager Binay Bajaj told Electronics Weekly. "For reliable operation where there is a lot of noise, you typically have to make the stylus 2.5-3mm, which is somewhat more than customers want. They want a ball-point [1mm] experience."
Branded maXStylus, the chip in the active stylus capacitively couples to the touch screen, synchronising itself to the emitted scanning waveforms and then injecting signals that the touch controller recognises as a stylus, and from which an accurate position can be calculated.
Bajaj did not want to describe exactly what signals are transferred, and the information is not yet openly available on the company website.
He did say that up to 12bits of data - 4,000 positions - is available in each axis.
In addition to position, the stylus transmits 256 levels of instantaneous tip force, adding another data dimension for, for example, signature recognition.
In use, stylus and touch can be implemented simultaneously - including features like two-fingered zoom.
Signals from a palm rested on the screen during stylus use can be suppressed.
On the subject of product pricing, Bajaj recalled a previous active stylus system with a shelf price of $80 which failed to catch on. "If you get it to $29.99 or even lower, many more people will be prepared to pay."
mXTS100 is the first chip in the family, supporting two stylus buttons, and expected to work for six months to a year from one AAAA cell (42.5x8.3mm dia 6.5g). A button press is required to initiate use.
Both Windows 8 and the Android 4.0 Ice Cream Sandwich will work with styluses and are supported by Atmel with this chip.
