How to set Atmega32 fuse bits

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#1
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Pls, I need help on how to set fuse bits of Atmega32. Am interfacing 12MHZ Crystal oscillator. Am working on an alarm clock system. I need help on how to disable the internal clock of the atmega32 and use 12MHZ crystal oscillator. Setting the fuse bits is giving me problem.

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Last Edited: Sun. Dec 8, 2019 - 05:46 PM
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http://www.engbedded.com/fusecalc/

 

When you say '12MHz crystal oscillator', what precisely do you mean? Is it just a 12MHz crystal and two load capacitors, or is it an actual oscillator module that requires power? A picture might resolve any questions.

 

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I have attached a picture

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That is a crystal, not a crystal oscillator! It forms part of an oscillator.

 

Select "Ext. Crystal/Resonator High Freq " on the website I linked to.

 

fuses: low 0xCE, high 0x99

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Sorry am a newbie. Do u mean I should search for 'Ext. Crystal/Resonator High Freq'

Xxxxxx

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click on the link in post #2

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I can't see any link. Pls explain. I joined this forum today so I don't really know my way around. Thanks for ur assistance.

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It is the very first text line in message #2.

 

Jim

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

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Okk, have seen it. I didn't observe properly. Thanks

Xxxxxx

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After imputing atmega 32. I didn't see any box or link that contains 'ext crystal'

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After clicking the link, I inputted the atmega32 but I don't see any box for 'ext crystal'. Pls explain.

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The drop down box under ‘features’. You also have a choice of startup time - this is less critical.

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External Crystal is one of the 16 selections for the system clock.  The one of 16 selection is made by changing the low fuses CKSEL3...CKSEL0.  The chart of the 16 selections is in the Mega32 datasheet somewhere.   Do a PDF search for CKSEL until you find it.

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Should I select any of the 'ext crystal/ high freq' . There are different values of start up time and 'CK and 'SUT'

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Ok

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What did I say in post #12?

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Ok am sorry

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Have successfully inputted the low and high fuses. What is the next step?

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What do you mean? If you’ve programmed the fuses into the mega32, it will expect an external crystal connected to it unless it won’t work anymore.

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I actually locked the previous micro controller I had. I will try these fuse settings on the new one and give you feed back.

Xxxxxx

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There is a tutorial on how to unlock your mega32. Anyways, get your current one working and you can use that to unlock the other.

 

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Ok

Xxxxxx

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Whoever came up with these names had loose rocks (or crystals) in their head.  Your typical choices are:

 

a) INT RC OSCILLATOR 
b) EXT CLOCK  
c) EXT CRYSTAL OSCILLATOR  
d) EXT FULL SWING CRYSTAL
e) EXT LOW FREQ CRYSTAL

 

a) is self-explanatory and generally a poor, or even unusable, choice when precision timing is needed, like UART applications
b) is self explanatory --it is a single-wire clocking waveform that comes from digital logic or from a crystal oscillator "module".
c) is ridiculous, since b is the choice for a crystal oscillator module.  This is uses a two-terminal crystal connection, not an oscillator module.
d) is similar to c, except the drive level is increased, giving some performance & compatibility benefits.

 

so C,D,E are for crystals & B is for an oscillator...got it?
e) is for slow operation, such as 32.768 KHz watch crystals

 

They should have just called (c) EXT CRYSTAL, so it is not mistaken for b & vice-versa

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Mon. Dec 9, 2019 - 12:58 AM
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If you do get "locked out" of an AVR in future read this:

 

https://www.avrfreaks.net/forum/...

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Thanks Clawson

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