Systems and methods for measuring time or capacitance

A system, comprising:

• a first capacitor;
• a first switch to selectively connect the first capacitor to a first high impedance node or a first low impedance node;
• a second capacitor;
• a second switch to selectively connect the second capacitor to a second high impedance node or a second low impedance node;
• an analog-to-digital converter (ADC) to perform differential voltage measurements between the first capacitor and second capacitor;
• control circuitry to:
• maintain the system in a ready state in which:
• the first capacitor is charged;
• the first switch connects the first capacitor to the first high impedance node;
• the second capacitor is discharged;
• the second switch connects the second capacitor to the second high impedance node;
• in the ready state of the system, control the ADC to perform a pre-event voltage measurement between the charged first capacitor and discharged second capacitor;
• determine an event start;
• in response to determining the event start:
• control the first switch to connect the first capacitor to the first low impedance node, causing a partial time-dependent discharge of the first capacitor;
• control the second switch to connect the second capacitor to the second low impedance node;
• determine an event stop, wherein a time between the event start and the event stop defines an event duration;
• in response to determining the event stop:
• control the first switch to connect the first capacitor to the first high impedance node;
• control the second switch to connect the second capacitor to the second high impedance node;
• control the ADC to perform at least one post-event voltage measurement between (a) the first capacitor, having partially discharged during the event duration, and (b) the second capacitor;
• and
• calculate the event duration based at least on (a) the pre-event voltage measurement and (b) the at least one post-event voltage measurement.

A method, comprising:

• setting a first capacitor to a charged state;
• setting a second capacitor to a discharged state;
• performing a pre-event differential voltage measurement between the first capacitor in the charged state and the second capacitor in the discharged state;
• determining an event start;
• in response to determining the event start:
• connecting the first capacitor to a first low impedance node to effect a partial time-dependent discharge of the first capacitor;
• and
• connecting the second capacitor to a second low impedance node;
• determining an event stop, wherein a time between the event start and the event stop defines an event duration;
• and
• in response to determining the event stop:
• performing at least one post-event differential voltage measurement between (a) the first capacitor, having partially discharged during the event duration, and (b) the second capacitor;
• and
• calculating the event duration based at least on (a) the pre-event voltage measurement and (b) the at least one post-event voltage measurement.