The CT515 series is a counter/debouncer chip that adds 5 counter input channels to the OWL2pe, Basic Stamp, Propeller, Arduino, or other microcontroller system. The CT515 allows the µC to offload the tasks and to focus its resources elsewhere. On command, the CT515 delivers the accumulated counts for further processing.
The 5 channels can be used to monitor rain gauges, anemometers, flow meters, traffic counters, or any such device that closes a switch or generates pulses at a low rate. Low rate means less than 500 Hertz, 1ms high and 1 ms low.
The CT515b is the most recent version. It has a maximum frequency response of 500Hz. The high and low levels must be at least 1ms long. It is good for modern flow meters and the current version of the Davis vantage pro anomometer.
The CT515a version has a slower response than the CT515b. It is good for slow, bouncy mechanical switches. It has a maximum frequency of 120Hz.
The CT515w (weather station version) is the same as the CT515b but one of the 5 channels is an analog channel for a wind vane.
Debouncing is important for mechanical switches, which often bounce at the instant they are closed or released. Bounce can generate multiple pulses into the attached electronics. The CT515 ignores the rapid changes and responds only to stable levels. The CT515 is set for a debounce interval of one millisecond. Debouncing is also important where sensors or buttons are connected via long wires that might pick up electrical noise.
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