The 74HC4017; 74HCT4017 is a 5-stage Johnson decade counter with 10 decoded
outputs (Q0 to Q9), an output from the most significant flip-flop (Q5-9), two clock inputs
(CP0 and CP1) and an overriding asynchronous master reset input (MR). The counter is
advanced by either a LOW-to-HIGH transition at CP0 while CP1 is LOW or a
HIGH-to-LOW transition at CP1 while CP0 is HIGH. When cascading counters, the Q5-9
output, which is LOW while the counter is in states 5, 6, 7, 8 and 9, can be used to dr
