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Android phone Touchscreen Sampling rate - signature capture

Posted on 2011-03-10
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Last Modified: 2013-11-21
Hi,
we have a call centre application that has a remote access service that I can update calls from a mobile device. As part of our call update we can also capture signatures, we would like to use something like a Samsung Galaxy S to do so (reasonable compromise in terms of price vs performance) but have an issue with the quality of the signature in that they are not smooth, they have lines instead of curves - picture trying to draw an S but ending up with a 5 etc.

This issue is not apparent on iPhone 3Gs or 4 (and as the 3Gs only has a 600Mhz CPU doesnt seem performance related) but we can't justify the additional cost of these devices (will make the project cost £1000's more).

I wonder if there is any way of increasing the sampling rate on the Android device so that it collects more x/y co-ordinates and therefore produces smoother signatures?

The call centre signature app is developed in Java and the developer is unable to assist, having got to the point of testing that the iPhone works but any Android devices I've tried (HTC Desire HD, Motorola Milestone & Envy as well as the Samsung). So I think the only option I can now pursue is if there is any way to make the Android phones sample for touch screen inputs more often. I'm hoping somebody knows of a tweak app or hidden setting that will allow me to change the sample rate.
I have searched for how to achieve this but aside from another couple of people asking a simliar question can't find any resources for this.

Any pointers greatly apprectiated - either to a way of setting the sampling rate or perhaps a way of putting the question to a more suitable Google / Android development group.

Thanks in advance!
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Question by:QuissEngineer
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6 Comments
 
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pmasotta earned 2000 total points
ID: 35335692
The Galaxy uses an Atmel maXTouch touchscreen
The Android kernel driver source code is mxt224.c
http://android.git.kernel.org/?p=kernel/samsung.git;a=blob;f=drivers/input/touchscreen/mxt224.c
the maXTouch is an interrupt driven i2c device; mxt224_irq_thread() is the driver working thread.
From the Atmel mxt224 datasheet
http://www.atmel.com/dyn/resources/prod_documents/9530S.pdf
Scan speed:
 Maximum single touch >250Hz subject to configuration
 Configurable to allow power/speed optimization
Response time:
 Initial Latency <10 ms, for first touch from idle, subject to configuration.

As you can see the driver is responsible for the problem you mention
See the next link; these guys experienced a similar problem that was solved after recompiling the driver
with a better strategy on when passing the mxt224 config parameters.
http://forum.cyanogenmod.com/topic/18431-tuning-driver-to-deal-with-unresponsive-touchscreen/


This analysis was performed for the Galaxy S but you get an idea how this issue can be traced
for any other device
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