Guard Sensor implementation with two CY8CMBR3116 supporting 20 buttons

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PeMa_1184626
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On the board I designed, two  MBR3116 are fitted to support 18 buttons. Each group of 9 buttons ( 3 row x 3 column)  is surrounded by its corresponding shield. Keypad is 3 row x 6 x column

The distance between buttons is 22 mm and the buttons diameter is 12 mm.  There is a GND trace separating two shields to prevent cross-talk.

I would like to include Guard sensor. If I select rectangle loop for Guard,  I cannot run two Guard traces plus shield and GND tracks between grouped sensors as 22 mm spacing is not enough.

I have two questions;

1) Does Guard sensor have to be a loop? Can I use 'C' shape around left group of buttons and mirrored 'C' around the right group?  

2) When the Guard sensor is scanned, is the shield active or disabled? In other words, Guard is dealt with same as any other button?

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

Hello PeMa_1184626

1) Does Guard sensor have to be a loop? Can I use 'C' shape around left group of buttons and mirrored 'C' around the right group?

-> No, Guard sensors need not be a complete loop. You can use a 'C' shaped outline around the sensors and this will work

2) When the Guard sensor is scanned, is the shield active or disabled? In other words, Guard is dealt with same as any other button?

-> Yes, shield will be active and a guard sensor is dealt with the same way as any other sensor.

Best regards

Hari

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