Need help in changing oscillator

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Hi i am using atmega 16. I have wasted 5 atmega 8 and 3 atmega 16 for making mistake in changing crystals.

please tell me a standard procedure to change external crystals in atmega 16.

i mean i connect 16mhz crystal with atmega 16 and then change fuse bits in extreme burner software. how i come back to built in 1 mhz? will i have to remove the crystal first and then change the fuse bits for 1mhz?
or i should keep the crystal in xtal1 and xtal2 with capacitors and then change the fuse bits...

also tell me the difference between oscillator and crystal if there are any

please tell me in details. if any link or forum post might be helpful, post here please.

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You populate the pcb with the 16MHz crystal and two 22pF capacitors. (and all other components especially 100nF decoupling capacitors)

Then you choose sensible software with a reliable hardware programmer.

Set the correct clock fuses. e.g. CKOPT + "Ext. high frequency crystal"

Everything works fine.

David.

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Didn't get the decoupling capacitor.
Is extreme burner software reliable?
what are other burner softwares i may use?

Is there any process to get out from locked avr?

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Quote:

Is there any process to get out from locked avr?

Recovering from a "locked out" AVR

(bottom line: never ever mess with RSTDISBL unless you really, really know what you are doing - anything else is pretty easy to recover)

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There is a key point you need to understand, There MUST be a working oscillator if you are going to program the IC. Here are cases where there is no working oscillator:

1) Internal RC oscillator is running. You change the fuses to work with an external resonator (crystal) but no crystal installed. Reset. Now, the MCU tries to work with external resonator, there is none, so you can no longer program it.

2) External oscillator is running. You are going to change to internal oscillator, so you remove the crystal. Now, when you try to program, there is no running oscillator. You can no longer program it.

In the context of MCUs, an "external oscillator" is a completely stand alone device. They typically have 4 pins. They require power and will oscillate even if not connected to an MCU. It takes only one connection (plus ground) between the oscillator and the MCU.

A crystal is a frequency determining device. It cannot oscillate without a companion amplifier. With an MCU, you also need two capacitors. There are two connections between the crystal and the MCU. The crystal will not oscillate without a powered MCU.

Hope this helps
Jim

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