Which resonator is best

[The Master]

I dont really have a specific model. I was looking at a datasheet for PIC16f84A just now but im not garunteed to be using that.

Having the extra I/O pins sounds like a good idea. I might be doing a few things where that would be helpfull. I like saving on PCB space too. What about with PWM though? I guess that is timing critical and i had to use a 16MHz resonator before. Im not sure that the small PICs i use would have above 4MHz built in.

Whats and "RC" osc?

80MHz :O wow! Heres me never gone above 16MHz before.

What about these 2 pin ones i keep seeing on rapid. Do they work in the same kind of way?

[mister_e]

My favourite 8 pin is the PIC12F683.. it has the PWM module built-in and can run up to 8MHz internal OSC... really nice device.. ADCs, comparator as well.

Forget the 10+ years obsoleted PIC16F84A device , use his big brother 16F628A (even if almost obsolete as well) or 16F88, PIC18F1320.. oh well so much in the list I keep 50 different model for 10f to 18F, 'round 20 for DsPIC and PIC32.

I suggest you to have on hand both 16F88 and 18F1320.

PWM.. not as this critical.. unless you REALLY need it accurate, the internal OSC worked for me pretty well in the past.. and still. My PICMultiCalc could be handy, just go on my website to download it.

RC osc. it's an oscillator built with Resistor and Capacitor. Knowing their temperature variation, you may use it or not. It always depend where and how you will use it. As i said, some, see most, newer device says to be 1% accurate... erm... look the whole datasheet and make your own conclusion. To me accuracy=crystal... but as i said... many application will run anyways with the internal OSC.

Just post your part# and we will have a look at.

[The Master]

Ive never used the 2 pin resonators before but some can be found here http://www.rapidonline.com/Electroni...5/kw/resonator. Why do some have 2 and some have 3 pins?

I dont really have any PIC chips that arnt in use. Just a few 16F84As and some 40 pin ones (cant remember the number). I should get a few in i suppose.

PICMultiCalc. Sounds familiar. I remember downloading something from your site that deals with baud rates (proably the same thing).

I think it depends what you mean by "Critical". I took it to mean it has to run at a certain speed or it wont work as intended. It will just be fading bulbs though. Its not like anyones life depends on it.

I had no idea that a PIC16F84A was so obsolete. Everywhere still sells them round here. Usually as soon as something new comes out you can never find the old ones

[mister_e]

Most of those 3 pins ceramic resonator i know have built-in capacitors. Those you post above don't, so you'll have to add 2 extra capacitor to make it work.

16F84(A) is popular 'cause it's the first Flash one (16C84). Many code example here and there in ASM. But you don't want to use it for a new project unless you don't have access to something else. Most newer model are also cheaper... see WAY cheaper. Good enough for a pin board

16C54 have been popular as well.. now they have 16F54

[The Master]

What do those codes actually mean? Is the first number and letter like a version number and the second number like the type?

Sorry to get back into this one again but how do i know what type of chip to use? The main reason im using a PIC16F84A is because ive used it in the past and its always worked fine. I dont like thinking that way. Im all for changing to make things better but here i dont know what to change to. You have given me a few examples but how did you know which ones do the same thing? I know the datasheets tell you but i dont believe that you sit there reading every possible datasheet to find the chip you want

I think ill stick with 3 pin ones then. I dont want any extra components taking up room/money.

[The Master]

What kind of temperatures affect them? Are we talking 1 or 2 degrees could alter it or like 20-30 degrees? Most of my stuff would remain at more or less the same kind of temperature give or take a few degrees.

[mister_e]

PIC16F84 don't do much and absolutely need an external crystal+MCLR connection.. 16F628 have comparator, MSSP, USART, no real must for external MCLR (this gives 1 i/o for free), can use it's own internal osc (that's 2 more i/o for free) and so on. More with PIC16F88, and a bit more with 18F1320. and there's still the codespace...

There's some temperature curves in the datasheet you can refer to. I still repeat, unless you need a real timing accuracy (e.g. high speed asynch serial comm), internal osc may be just fine. 16F88 one can run up to 8MHz, 18F1320 up to 32MHz!

[skimask]

As i said, some, see most, newer device says to be 1% accurate...

Just a 2nd opinion...
All of my 18F4620's, when running on the internal 8Mhz & 4xPLL (giving 32Mhz on the chip) are well within 1% and have always worked well when using a serial interface. The datasheet says +/- 10% over the full voltage/temp range, but again, at least 1% for the 100-ish I've used so far (maybe one or two of those have been a bit out in the weeds and needed tweaking, but I don't remember any off the top of my head).