Touch detection techniques for capacitive touch sense systems

An apparatus, comprising:

• a capacitance sense interface including a capacitance sensor having a baseline capacitance value associated with the capacitance sensor;
• a capacitance measurement circuit coupled to the capacitance sense interface to sense a measured capacitance value of the capacitance sensor and output a signal indicative of the measured capacitance value;
• and
• startup logic coupled to analyze the signal to determine whether the capacitance sensor was activated during a startup phase and to adjust the baseline capacitance value in response to determining that the capacitance sensor was activated during the startup phase, wherein the startup logic determines whether the measured capacitance value crosses a negative threshold value for a predetermined period of time, wherein the predetermined period of time is greater than a single clock cycle.

A method, comprising:

• measuring a capacitance value of a capacitance sensor within a capacitance sense interface to generate a measured capacitance value;
• analyzing the measured capacitance value to determine a baseline capacitance value for the capacitance sensor;
• updating the baseline capacitance value based at least in part upon a weighted moving average of the measured capacitance value;
• analyzing the measured capacitance value to determine whether the measured capacitance value drops below the baseline capacitance value by a negative threshold value for a predetermined period of time, wherein the predetermined period of time is greater than a single clock cycle;
• and
• updating the baseline capacitance value based on the measured capacitance value measured after the measured capacitance value dropped below the negative threshold value.