Counter Debouncer

(CT515)

• simultaneous and continuous debouncing and counting of all 5 inputs. Frequencies up to 500Hz, high time>1ms and low time>ms.
• internal 20kΩ pullup resistors for each switch, except c4 (requires an external pullup). Stronger pullups can be added externally.
• 3.3V to 5V power supply, low power, 10 microamps while waiting for pulses. No crystal required, uses PIC675 internal oscillator. 1.2 milliamps while counting and during communication with processor.
• connection to microcontroller via a single pin with pullup resistor, data transfer at 9600 baud, open baud mode, true (stop bit is a low level), paced so that the BASIC Stamp can receive.
• Communication Protocol:
  • µC brings the comms pin low >1ms then high. CT515 captures the current count values and responds with 12 bytes:
    • $80 as preamble to verify baud rate
    • $xx individual bits reflect the current state of all 5 inputs
    • $aaaa $bbbb $cccc $dddd $eeee 16 bit result from each of the 5 channels, each result least significant byte first.
    • At the instant of capture, all 5 counters are reset to zero.
• Available as DIP8 or soic8 package.
• Special versions are available, for example:
  • longer debounce interval. Old fashioned flow meters have long reed switches that require a much longer debounce interval;
  • one input channel can be converted to analog to digital function in order to acquire wind vane analog output along with speed.
  • debouncing can be disabled for faster counting.