Do I need an oscillator?

Hello All,

I haven't finalized the design, but I'm thinking I will be using the 16F819. I have a module that I'm making that will do certain functions when certain inputs are activated, but I wanted to ask about one feature I was going to be implementing and needed to know if the oscillator was necessary.

The one feature this module will have is that when a certain input is activated, the module will begin a timed output. After this time expires, the output will turn off. However, the twist is this; because I want to monitor the other inputs in 1/10th second increments, do I even need an external oscillator? The pic usually handles short counts quite accurately. I would just use a counter to keep track of the number until say 5 minutes is reached. It doesn't have to be accurate, the timed output is simply to prevent excessive draw on the battery.

So, using a pause 100 command along with a counter seems pretty straight forward to me, but I just wanted to run it past you guys to see if I was missing something. If another input is activated, the timer would simply exit and reset it's count.

My logic seems sound unless someone objects.

Thanks,
Tony

Hi Tony,
As long as the accuracy of the internal oscillator is good enough for you then it's fine.
Short times or long times doesn't matter from that perspective, if the oscillator is 2% "out" it's 2% "out". Short or long delays, no difference, it's still 2%.

/Henrik.

That's what I thought, but I just wanted to be sure. Thank you.

Tony