Skip to Content

Preparation

Last modified by Microchip on 2026/03/19 14:08

Front Panel

  • The Front Panel should securely adhere to the sensor Printed Circuit Board (PCB).
  • There should not be any air gaps. Air gaps:
    • Cause unit-to-unit variation.
    • Reduce sensitivity significantly
    • Cause unpredictable touch behavior
  • The assembly should be representative of the final product assembly; if not, retuning may be required for production.

External Resistor

Refer to the following table for the recommended initial series resistor configuration for tuning. If the target noise immunity is unknown, select the resistor value based on the power supply.

Information

Note: The resistor value may need to be changed during noise tuning.

 Self-capacitanceSelf-capacitance + Driven ShieldMutual Capacitance
Targe Noise Immunity (Conducted Immunity)
High (10V)100 KΩ50 KΩ1 KΩ (100 KΩ internal).
Medium (3V)50 KΩ10 KΩ1 KΩ (50 KΩ internal).
Low (1V)1 KΩ1 KΩ1 KΩ (0Ω internal).
Power Supply
Battery Operated1 KΩ1 KΩ1 KΩ (0Ω internal).
Mains Power Supply10 KΩ5 KΩ1 KΩ (10K internal)

Power Supply

  • Initial touch tuning, such as charge time, sensitivity, etc., must be done with a stable power supply.
  • Use a bench supply to power the device until basic tuning is completed.

Project Generation

For tuning the touch sensor, it would be good to have a project with just the touch application and tune (debug) data available in MPLAB® Data Visualizer.

Refer to the Generate a Touch Project With MPLAB® Code Configurator (MCC) Melody page for generating touch projects for 8-bit or 16-bit MCUs.

Refer to the Generate a Touch Project With MPLAB® Code Configurator (MCC) Harmony page for generating touch projects for 32-bit MCUs.

Refer to the Guide to View Touch Tune Data page for information on viewing touch tune data in MPLAB Data Visualizer.

While creating the project:

Configure the touch pins.

Configure the debug pins.                 

Enable the Sensor Charge Time auto-tune option.

Information

Note: Not all devices support the auto-tune feature. In such cases, refer to the manual steps described in the charge tune section.

Information

Note: Auto-tune charge time option must be used only for the initial development. When the tuning is completed, and when the system is ready for testing, the auto-tune option must be disabled, and manual feed values must be used.

Enable the Frequency Hop auto-tune option (if Target Noise Immunity is medium or high).

Keep the other parameters to default values.

Download a copy of the project with the Sensor Charge Time auto-tune option disabled.

Back to Top