I am working on an automation project. I need to sense the position of an object as it passes under a dispenser, delay a period of time which will depend upon the speed of the conveyor, then open the dispenser. In some instances this will all occur within 10-20 ms. The speed of the conveyor will be measured by an additional sensor. I can do this currently, however, as I have it now, in certain conditions, it will "miss" the object. I am trying to do this and a few other "bell and whistle" type things using a Pic16F877a, and I thought I had it. The problem seems to occur because at certain speeds, the dispenser is in an open sequence at the same time that the next object is interrupting. Should I use a 555 to time the dispenser opening so that the pic isn't trying to perform more than the one action at a time. Forgive me for not being as technical as some, I am a newbie, only versed in my compiler commands and the pic operations. I would appreciate any help I can get. Thanks.