Hi,
I am trying to design a counter that counts to 999. It counts up when one button is pressed and down when another button is pressed.
I have integrated three 4510B counter chips and their decoders connected to seven segment displays, with monostables to change the up/down count connection and maintain its change for a long enough amount of time to send a count pulse within it.
This all works but when i switch on the circuit, the bottom two counters (tens and hundreds) start on nine. Also, after pressing the reset and beginning to count, the counters carry out one pulse to early, so the counter goes from 9 to 19 to 10 to 11.
Any ideas what I have done wrong or how to fix this?
Screenshots of the circuit and waveform attached:
I am trying to design a counter that counts to 999. It counts up when one button is pressed and down when another button is pressed.
I have integrated three 4510B counter chips and their decoders connected to seven segment displays, with monostables to change the up/down count connection and maintain its change for a long enough amount of time to send a count pulse within it.
This all works but when i switch on the circuit, the bottom two counters (tens and hundreds) start on nine. Also, after pressing the reset and beginning to count, the counters carry out one pulse to early, so the counter goes from 9 to 19 to 10 to 11.
Any ideas what I have done wrong or how to fix this?
Screenshots of the circuit and waveform attached: