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PSoC™ 4 Forum Discussions

dabo_4430311
Level 2
Level 2
10 replies posted 10 questions asked 10 sign-ins

is there a precise guide or reference regarding how the scanning of a trackpad is performed (algorithm, computation of X-Y) when using capsense v7.0 with SmartSense mode?

Is it possible that a psoc 4 (CYBLE214015-01) scanning 7-7 or 8-8 rows-columns trackpads saturates and doesn't have enough power for the scanning? sometimes only rows and sometimes only columns are detected, does the scanning happens simultaneously or sequentially?

data are visualized through capsense tuner

thank you

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Hari
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi dabo_4430311

In your implementation, I am assuming that you are using CSD track-pad and not CSX track-pad.

SmartSense is just a firmware algorithm that sets the tuning parameters automatically so that it is easier to get started with the design and provide an initial set of parameters so that manual tuning is also easier.

Scanning in a CSD touchpad/trackpad happens sequentially in all devices. The rows and columns are scanned separately. The component then uses the information obtained to determine the row and columns which are active and subsequently determines which portion of the touchpad was active to determine the XY coordinates.

The issue with CSD touchpad is that if two portions of the touchpad are touched at the same time, say we touch (X0, Y1) and (X1, Y0) from figure below at the same time, then the component detects that 4 areas were touched since two rows and columns were active. This effect is called "ghost touch".

pastedImage_0.png

To eliminate this issue, CSX touchpad is recommended. However, if multi touch feature is not required, CSD touchpad is better since the scan time is less in CSD touchpad.

Best regards,

Hari

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1 Reply
Hari
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi dabo_4430311

In your implementation, I am assuming that you are using CSD track-pad and not CSX track-pad.

SmartSense is just a firmware algorithm that sets the tuning parameters automatically so that it is easier to get started with the design and provide an initial set of parameters so that manual tuning is also easier.

Scanning in a CSD touchpad/trackpad happens sequentially in all devices. The rows and columns are scanned separately. The component then uses the information obtained to determine the row and columns which are active and subsequently determines which portion of the touchpad was active to determine the XY coordinates.

The issue with CSD touchpad is that if two portions of the touchpad are touched at the same time, say we touch (X0, Y1) and (X1, Y0) from figure below at the same time, then the component detects that 4 areas were touched since two rows and columns were active. This effect is called "ghost touch".

pastedImage_0.png

To eliminate this issue, CSX touchpad is recommended. However, if multi touch feature is not required, CSD touchpad is better since the scan time is less in CSD touchpad.

Best regards,

Hari

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