Verify crystal is working

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Hi,
Since I select the fuse bit that set the micro to use the external crystal the avr dragon can't enter programming mode again. The crystal is: http://pt.mouser.com/Search/Prod...

My circuit:

How can I verify if the crystal is oscillating? If it help I have the following logic analyser http://dangerousprototypes.com/d...

Thank you

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Stick an X10 scope probe on the pins?

Imagecraft compiler user

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metRo_ wrote:

How can I verify if the crystal is oscillating?

A multimeter and high speed diode (1N4148 / BAW62 etc) can give a low-loading means of checking for crystal operation.
Meter from XPins-GND and from Vcc-XPins(diode right at the Xpin) and short/unshort the crystal and check the Meter change.

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metRo_ wrote:
Since I select the fuse bit that set the micro to use the external crystal ...

Chances are good that you did not. Do you recall the actual values that you programmed?

Oh and your load capacitors are way too large, but it should still oscillate.

 

In consideration of others, please RTFM!

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A common error is to choose "external oscillator" which your words suggest. It needs to be "high frequency crystal or resonator", or some words to that effect.

An external oscillator is a stand-alone powered device that will make a clock signal with or without an MCU.

See here for ways to recover:

https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=106325

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Quote:

How can I verify if the crystal is oscillating?

"modern" AVRs such as 328 have a fuse called CKOUT and a pin called CLKO (PB0 for 328). Unless you are real tight on I/O it's a good idea to set that fuse and leave that pin clear so you can always easily scope the pin to find out the exact CPU operating frequency.

(of course to do ISP to set the CKOUT fuse the AVR has to be clocking OK in the first place - so maybe best to set that fuse first before messing about with others).

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bobgardner wrote:
Stick an X10 scope probe on the pins?
Don't have a oscilloscope :s

Who-me wrote:
metRo_ wrote:

How can I verify if the crystal is oscillating?

A multimeter and high speed diode (1N4148 / BAW62 etc) can give a low-loading means of checking for crystal operation.
Meter from XPins-GND and from Vcc-XPins(diode right at the Xpin) and short/unshort the crystal and check the Meter change.

Do you have a schecmatica that I can look at?

jpmargis wrote:
metRo_ wrote:
Since I select the fuse bit that set the micro to use the external crystal ...

Chances are good that you did not. Do you recall the actual values that you programmed?

Oh and your load capacitors are way too large, but it should still oscillate.

The arduino ones:

Low Fuse 0xFF
High Fuse 0xDA
Extended Fuse 0×05

I used this formula for capacitors C=2xCl-Cs, so Cl = 9pF and Cs = 6pF (can vary between 5 and 10pF according to http://api.viglink.com/api/click...)
C = 2x9 - 6 = 12pF

ka7ehk wrote:
A common error is to choose "external oscillator" which your words suggest. It needs to be "high frequency crystal or resonator", or some words to that effect.

An external oscillator is a stand-alone powered device that will make a clock signal with or without an MCU.

See here for ways to recover:

https://www.avrfreaks.net/index.p...

Jim

I'm going try to recover so I can enable this:
clawson wrote:
Quote:

How can I verify if the crystal is oscillating?

"modern" AVRs such as 328 have a fuse called CKOUT and a pin called CLKO (PB0 for 328). Unless you are real tight on I/O it's a good idea to set that fuse and leave that pin clear so you can always easily scope the pin to find out the exact CPU operating frequency.

(of course to do ISP to set the CKOUT fuse the AVR has to be clocking OK in the first place - so maybe best to set that fuse first before messing about with others).

Thank you all :)

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Change the capacitors value to 18pF and now it works but now I don't understand why I'm using this value :S

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See this:

http://www.adafruit.com/blog/2012/01/24/choosing-the-right-crystal-and-c...

The crystal datasheet should specify a load capacitance (CL), and as it says, assume Cstray = 5pF.