You may have to give us more details of what you are trying to accomplish. No one would "play" with you and build command by command your code or what evere.

Give more input. What is you input signal. Is it Pulse? Is it from a PC? Is it from a pot?

You are not clear. I said that your variable would need a value. Pulsin would give a value to ch1 but is it what you really want to do?

Ioannis