10MHz clock oscillator

Does any one have a schematic for a clock oscillator suitable for CMOS devices?

I can fine plenty of theoretical schematics for Pierce Oscillators but no practical implementations of them with component values and names.

Can you be a little(*) more specific, "clock oscillator" is a very broad description.

(*) as specific as possible is always good.

And you know quartz oscillators are stock items (admittedly all surface mount)...

MarkT: Can you be a little(*) more specific, "clock oscillator" is a very broad description.

(*) as specific as possible is always good.

Specifics......

I want to apply a 10 - 16 MHz clock signal to the xclk pin of an OV7670 module to see if I can get any response out of it over TWI.

The datasheet says that the minimum clock speed is 10MHz.

And it is not possible to attain those speeds out of a arduino pin via pwm or the TimerOne library.

Just google '10 MHz crystal oscillator'... and select 'images' for the search.

Southpark: Just google '10 MHz crystal oscillator'... and select 'images' for the search.

That is what I have been doing but all I seem to get are theoretical schematics, not a specific schematic where some one has specified, in particular, what component they used for the 'not' gate, what voltage they used and how they connected it up to the input that required the clock signal.

I similar need specifics on how to do this.

I have tried a CD4069 but my multimeter measures the frequency in the tens of kHz range....although it may not be accurate enough. Either way it does not bring my OV7670 to life.

How about using one of these as you can then adjust the clock from the Arduino.

The simplest thing is to buy a "10MHz Crystal Oscillator", like http://www.allelectronics.com/make-a-store/item/crx-103/10-mhz-crystal-oscillator/1.html These are typically 4-pin devices - you apply power to two pins, and 10MHz comes out one of the remaining pins. A wide range of frequencies and physical sizes are available, they show up relatively frequently even at hobby vendors, and they're not very expensive even from "real" vendors (although: shipping.)

A Pierce Oscillator is a thing that drives a crystal; that's fine if you have an appropriate crystal. If you don't, you might as well buy the oscillator instead...

If you just need "some frequency between 10 and 16MHz" and it doesn't have to be exact, you could use a simple RC oscillator made up of CMOS gates. See https://www.fairchildsemi.com/application-notes/AN/AN-118.pdf One of the two or three inverter circuits with R=2k and C=27pF should give you about 10MHz with modern CMOS logic like a 74hc14. (again, if you don't have a parts box with the pieces, you might as well buy the packaged oscillator.)

Here is one circuit.....

click here

The NAND gate is a two input NAND gate.... with both inputs tied together.... effectively a NOT gate (aka inverter). The capacitors are kind of small.

Best to take the output to a buffer circuit... voltage follower so as not to load down the oscillator circuit.

Riva: How about using one of these as you can then adjust the clock from the Arduino.

Already got something like that that I de-solderd from a tv circuit board. But I don't understand well enough how to actually used one other than with a stand alone Atmega328p chip (16MHz in that case).

westfw:
The simplest thing is to buy a “10MHz Crystal Oscillator”, like http://www.allelectronics.com/make-a-store/item/crx-103/10-mhz-crystal-oscillator/1.html
These are typically 4-pin devices - you apply power to two pins, and 10MHz comes out one of the remaining pins.
A wide range of frequencies and physical sizes are available, they show up relatively frequently even at hobby vendors, and they’re not very expensive even from “real” vendors (although: shipping.)

A Pierce Oscillator is a thing that drives a crystal; that’s fine if you have an appropriate crystal. If you don’t, you might as well buy the oscillator instead…

If you just need “some frequency between 10 and 16MHz” and it doesn’t have to be exact, you could use a simple RC oscillator made up of CMOS gates. See https://www.fairchildsemi.com/application-notes/AN/AN-118.pdf
One of the two or three inverter circuits with R=2k and C=27pF should give you about 10MHz with modern CMOS logic like a 74hc14. (again, if you don’t have a parts box with the pieces, you might as well buy the packaged oscillator.)

Well that is exceptionally helpful because I have been looking for some pre-solderd device along these lines - I have obviously been using the wrong key words in google and ebay. OV7670 is a CMOS device so I assume the clock signal has to be pretty stable and accurate what ever its frequency.

OV7670 is a CMOS device so I assume the clock signal has to be pretty stable and accurate what ever its frequency.

Video always uses quartz timing, whether CMOS or anything else, because the accuracy was required for broadcast modulation. There's nothing magical about CMOS and accurate timing - until you get to things like CPU's and computer busses where the timing is pushed right to the limit and clock jitter and skew are all important. Most (CMOS) microcontrollers have an RC oscillator option to reduce BOM costs in small embedded devices.

For instance small TFT displays don't care about their clocking much at all, and they are CMOS, but everyone drives them from a quartz crystal.