Espressif Systems ESP32-S2 Hardware Design Manuallines page 22

3. PCB Layout Design
• The electrode diameter (D) should be in the range of 8 mm to 15 mm.
• Hatched ground should be added around the electrodes and traces.
• The traces should be isolated well and routed away from that of the antenna.
In addition, ESP32-S2 touch sensor adopts a waterproof design and features proximity sensor function. Figure
shows an example layout of a waterproof and proximity sensing design.
Note the following guidelines to better implement the above functions:
• It is recommended that the width of the shield electrode width is 2 cm.
• Employ a grid on the top layer with a trace width of 7 mil and a grid width of 45 mil (25% fill). The filled grid
is connected to the driver shield signal.
• Employ a grid on the bottom layer with a trace width of 7 mil and a grid width of 70 mil (17% fill). The filled
grid is connected to the driver shield signal.
• The protective sensor should be in a rectangle shape with curved edges and surround all other sensors.
• It is recommended that the width of the protective sensor is 2 mm.
• It is recommended that the gap between the protective sensor and shield sensor is 1 mm.
• The sensing distance of the proximity sensor is directly proportional to the area of the proximity sensor.
However, increasing the sensing area will introduce larger noise. Actual testing is needed for optimized
performance.
• It is recommended that the shape of the proximity sensor is a closed loop. The recommended width is 1.5
mm.
Espressif Systems
Figure 20: Sensor Track Routing Requirements
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ESP32-S2 Hardware Design Guidelines V1.1
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