Texas Instruments Incorporated
Container disturbance filtering for capacitive liquid level sensing

Abstract:

An apparatus for filtering touches and disturbances of a container comprises a processing unit (PU) and computer-readable storage devices storing machine instructions. The PU obtains and sums together sensor values for a first sampling time from electrodes affixed to the container. The PU determines a difference between the sum for the first sampling time and a sum for a second sampling time, which is compared to a threshold representative of a change in capacitance due to a touch on the container. The PU determines whether the touch on the container has occurred at the first sampling time based on the comparison. If a touch occurred, the PU continues to obtain additional sensor values for additional sampling times and determine whether a touch on the container has occurred at the additional sampling times, until determining no touch occurred. The PU determines liquid level for the container after determining no touch occurred.