Wednesday, June 25, 2008

Cypress brings out new portfolio of capacitive multi-touch touchscreen solutions

Cypress TrueTouch Cypress announced TrueTouch™ capacitive touch screen solution based on the PSoC® programmable system-on-chip architecture. The products are categorized into three groups: Single-Touch, Multi-Touch Gestures, Multi-Touch All Point.

CY8CTSTxxx series is dedicated to single-touch solution just like conventional touchscreen controllers which detect a single finger. CY8CTSTxxx controllers support 25 X/Y sensor inputs and screen sizes upto 4". Sampling rate of each channel is 30 us. Therefore the actual frame rate of the touchscreen is 7.5 ms (about 133 Hz), which is enough for most touchscreen applications.

CY8CTMGxxx controllers support single-touch and multi-touch gesture recognition. I guess that Cypress just add some multi-touch gesture recognition moulde to CY8CTSTxxx to get CY8CTMGxxx controllers. It can be verified by the fact that most technical specifications are same except for multi-touch gesture support.

CY8CTSTxxx and CY8CTMGxxx are almost same as conventional touchscreen controllers while CY8CTMA120-56LFXI really makes differences. It can detect ten independent finger movements with upto 8.5" displays. However, CY8CTMA120 seems to have a critical problem from the perspective of scanning time. Datasheet says that it takes 120 us for the controller to detect a finger for each X/Y crossing. Note that the controller supports maximum of 45 X/Y sensor inputs. Therefore, if one configures a touchscreen with 20 by 25 spatial resolution, the total scannng time would be 60 ms (20 X 25 X 120 us; about 1.67 Hz). 1.67 Hz scannig rate is too slow to be applied to most applications. I hope Cypress prepare a solution for this problem.

By the way, Cypress suggests an interesting application of multi-touch. While people always say multi-touch zooming in/out and rotation, they introduce multiple location input for GPS appliances. It's quite fresh idea, isn't it?

Anyway, Cypress is now the first provider of multi-touch solution among capacitive touch sensor IC makers.

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