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Alexrs
Joined: 20 Feb 2012
Posts: 4
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 Posted: Mon Feb 20, 2012 12:35 am Post subject: Fuse bits |
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Hello.
I am Very new to Bascom. But that’s not an excuse to ask silly questions.
I am using Atmega 8 16pu chip.
Using the Avr studio v5.0 1223 to upload and set fuses.
Not having to much trouble with the programming at this time..
I can upload with no issues at all.
What I have issues with is Avr studio and the fuse settings.. I have BRICKED two chips trying to get it right.
I have done a lot of reading up on Avrstudio but there is nothing that helps me.
The High Fuse I am setting to D9 and the Low Fuse to E8.
The SUT_CKSEL setting i HAVE selected is EXTRCOSC_8MHZ_12MHZ_18CK_64MS.
Is there anyone can please advise on were I am screwing up.
Regards Alex |
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kimmi
Joined: 24 Feb 2006
Posts: 1922
Location: Denmark
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| Posted: Mon Feb 20, 2012 12:43 am Post subject: |
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Hi
do you have a crystal 8Mhz to 12Mhz connectet to M8 ? LOW = E8
You set fuse to use EXTERN crystal
Engbedded Atmel AVR® Fuse Calculator
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JC
Joined: 15 Dec 2007
Posts: 627
Location: Cleveland, OH
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kimmi
Joined: 24 Feb 2006
Posts: 1922
Location: Denmark
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| Posted: Mon Feb 20, 2012 3:31 am Post subject: |
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If you don’t have a Jtag, or STK500
You can use a external clock if you messed the fuses settings.
Connect a external clock (around 1Mhz) on the clock pin (XTAL1 PIN)
and reprogram fuse again
else read this
| Quote: | External RC oscillator setup
The frequency in this mode is calculated by formula f=1/(3RC) while C should be at least 22pF. If CKOPT is programmed (unchecked),
then Internal capacitor 36pF between XTAL1 and GND is enabled,
then there is only resistor needed.
Ft[MHz]=1000/(3·R1[kΩ]·C1[pF]) |
R1 = 1K
C = use internal Co 36pf CKOPT was unchecked
1000 / (3 * 1 * 36) = 9.25925926 Mhz
So you can add a 1K RES between +5V and XTAL1
+5V --- RES----XTAL1 PIN
Well its a try maybe it works I never tested this option on real hardware
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Alexrs
Joined: 20 Feb 2012
Posts: 4
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| Posted: Mon Feb 20, 2012 8:08 am Post subject: |
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Hi and thanks for replays.
Kimmi I have a 16 MHz With caps connected.
Thanks for the info on unbricking the chips.
Will check the crystal connections later on.
I have 1 more chip to play with then I will do something with the chips.
Regards Alex |
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kimmi
Joined: 24 Feb 2006
Posts: 1922
Location: Denmark
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| Posted: Mon Feb 20, 2012 8:57 am Post subject: |
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Hi,
If you have External crystal 16 mhz the fuse is WRONG
ATMEGA8 (not the L version its only 8Mhz)
the fuse must be :
HIGH = D9
LOW = 7F or FF if BODLEVEL unchecked
use Ext. Crystal/Resonator High Freq.; Start-up time: 16K CK + 64 ms the last one
not Ext. RC Osc. 8.0 MHz - 12.0 MHz; Start-up time: 18 CK + 64 ms
its for RC osc not crystal
RES and CAP as in my last post
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Alexrs
Joined: 20 Feb 2012
Posts: 4
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| Posted: Mon Feb 20, 2012 11:49 am Post subject: |
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Thank YOU.
Thats my error.
Sorry for posting in wrong Area.
Regards Alex |
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ajvuik
Joined: 28 Apr 2011
Posts: 46
Location: Netherlands
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