Guidelines: Crystal oscillator FAQ and manuals.
Read this page: - Application notes, basic information:
It was written by a great hacker and translated to many languages.
Read it please.
1) Be sure to know your PIC's datasheet well and read ALSO the notes with small letters under the text, because they are important. Many questions are answered there.
2) Maybe your problem is already described in the errata: http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1433
3) There are more application notes that describe the crystal oscillator operation: http://ww1.microchip.com/downloads/en/AppNotes/FACT001.PDF
This is the original BASIC PIC OSCILLATOR DESIGN. http://ww1.microchip.com/downloads/en/AppNotes/00838a.pdf
Almost the same as above, updated, but some information is missing. http://ww1.microchip.com/downloads/en/AppNotes/00849a.pdf
Basic PICmicro Oscillator Design, 24 pages of technical explanation and oscillographs from real oscillator circuits.
This is an advanced paper. http://ww1.microchip.com/downloads/en/AppNotes/00826a.pdf
Crystal Oscillator Basics and Crystal Selection, 11 pages, explanation of technical terms and deeper look at the physical hardware. http://ww1.microchip.com/downloads/en/AppNotes/00949a.pdf
(Making your oscillator work)
Nothing much to read, but contains a FAQ which the other app. notes don't.
Finally! Some good theory and simulation now at Microchip also! http://ww1.microchip.com/downloads/en/AppNotes/00943A.pdf
Beware that this app. note says that you have to read AN826 (FACT001, AN838 are also good) and AN849 first!
4) If you still don't have enough, there are some other application notes, you are advised to search for them on your own, so only two more:
Internal RC Oscillator Calibration: http://ww1.microchip.com/downloads/en/AppNotes/00244A.pdf
"OSCILLATOR SELECTION FOR ST62", datasheet number 2501, available at STMicroelectronics.
Be sure to know how crystal operation works before you ask that :). Because you would be asked to read the above mentioned documents. - What to do and what not to do.
1) Do place decoupling capacitors near each pair of power supply pins (usually the cheapest 100nF multilayer ceramic types).
2) If possible, avoid using breadboards. Keep tracks from PIC to crystal short, the same applies to capacitors.
Breadboards are a real nightmare to HF circuits... It adds so much L,C, and R (it may add unwanted inductance, capacitance and resistance) to the circuit that it's hard to predict how it will act. - What to write in your post:
What PIC you are using, __CONFIG bits setup, value of capacitors in the crystal oscillator, supply voltage. - What more?:
If you do not seem to find the information you were looking for in 5 minutes, please take another 55 minutes searching for that. Still no results? It is possible that there is no such information, try using the closest alternative datasheet of similat technology.
DO YOUR PROJECTS AND HOMEWORK ON YOUR OWN!
< Message edited by mfb -- Jan. 20, 2005 11:37:47 AM >