EE Times Under The Hood - October 8, 2007 - (Page 22) under the hood: MOBILE www.eetimes.com • www.techonline.com Capacitive sensing has a magic touch BY RICHARD NASS W hen you’re designing a handset, it’s all about how many features you can pack into a tiny space. The more features, the better, right? Not necessarily. Most of us are familiar with devices that are difficult to use because they have so many features packed into too small a space. for Verizon Wireless. LG Electronics developed parts of the firmware for this handset in conjunction with Cypress Semiconductor, and then used that code in several iterations of the handset. Most of the changes that LG made along the way had to do with the number of buttons and interfaces to be employed, so the overall technology and the details of how it’s implemented have remained consistent. The Cypress team first made con- That’s the fine line designers must walk—lots of features in a small space, but not too many features in too small a space. One way to clear this hurdle, as evidenced by the popular LG Chocolate phone, is to employ a capacitive touch sensor to handle most of the handset’s user input. This particular version of the Chocolate that I “disassembled” is also known as the LG VX8500, which is the model manufactured tact with LG in May 2005, extolling the virtues of the company’s PSoC (Programmable System on a Chip) architecture. The two teams went back and forth, eventually coming up with the final design requirements. Actual development began around August 2005, with the goal of having the product released to manufacture in October 2005. “The original requirements were somewhat unclear,” says Greg Virge, a firmware and applications engineer at Cypress. Often when a customer employs capacitive sensing for the first time, it’s all about understanding what they really need as opposed to what they think they need. That took a couple of 22 Electronic Engineering Times, TechOnline | October 8, 2007 http://www.eetimes.com http://www.techonline.com
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