PIC16F88 senior design

[Pic_User]

Hi AlaskanEE,

Welcome to the forum.

I'm a circuits electrical engineer and thus have never worked with programming or microcontrollers

You picked the right microcontroller for an analog guy. The PIC devices have comparators, voltage references, A to D converters, etc.. You are going to love these microcontrollers. A perfect fit with the analog world.

So the 16F88 doesn't have it's own internal oscilating crystal. Is there any way to get around creating an external oscilating circuit or is that a must?

You may have based this on what Dave correctly said:

External oscillating circuit is a must. The data sheet gives several examples. I like the crystals with built in caps, one part to do the job and the 20Mhz is cheap.

The only (out-side the PIC) components needed for the "External oscillating circuit", are a simple three terminal ceramic resonator or a crystal with two capacitors to ground.
Some of the serial stuff needs a more stable oscillator than the drifty one internal to the PIC. The one in the PIC is okay for a lot of projects.

Don’t give up on the forum, you are an equal member. Keep asking questions. That’s what it is here for. When a person comes along with a similar question, they won’t have to ask. Don’t forget to search for your question / answer before posting. Have fun. Learn.
-Adam-

[AlaskanEE]

Sorry skimask I was just trying to step gengerly in the forum since I'm new, but was trying to get my point across without ticking anyone off. I know it came off pansy, but I was playing it safe. I misunderstood what you were saying about the internal oscilator. I had skimmed the data sheet and accidentally lumped the statement "the PIC16F88 CAN be set to 20MHz" in with the preceeding paragraph saying that the PIC's internal oscilator can be set to multiple frequencies. So when you said that the DEFINE OSC command doesn't set anything to 20MHz I was confused and the sentance "so the 16F88 doesn't have an internal oscilator" should have had a question mark cause I was asking. Also I was just trying to let everyone know what I'm doing and show the code I was using so that they could comment on what I had done, if it would work or not. I wasn't trying to get everyone to write my code for me and I'm sorry for my lack of clarity on that point. Again sorry for the miscommuniactions and lack of clarity. Also thanks Adam for the suport, I just blew this up too quickly, was getting frustrated with the programming. Chalk it up to experience I guess.

[mackrackit]

I should have been a little more clear. If you want something reliable, external oscillator is a must. Being that serial communications are involved. The internals work fine but sometimes the timing will get a little off.

The oscillator you choose will need to be defined in the *.inc file for the chip you are using along with the other fuses. In the *.bas file you tell PBP what the oscillator speed is for timing. These are the same yet different.

You will find a line in the *.inc file something like this.

__config _XT_OSC & _WDT_ON & _PWRTE_ON & _BODEN_ON & _LVP_OFF & _CP_OFF

Look at the data sheet and it will tell you what each one does.