| 摘要 |
Methods and systems for detection of zero crossings in a signal are described. For example, true zero crossings in an alternating voltage power source signal can be detected in the presence of noise pulses. The zero crossing detections are performed by establishing a value of a signal status counter, and at a repeating interval if the signal is a logic low value, the value of the signal status counter is decremented if the signal status counter is greater than a first value otherwise a flag is set to enable detection of a zero crossing in the signal. In addition, at the repeating interval, if the signal is a logic high value, the value of the signal status counter is incremented, and if after incrementing the signal status counter is equal to a second value and the flag is set, a zero crossing of the signal is declared. |
