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 Posted: Mar 14, 2010 - 05:26 AM |
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Joined: Mar 07, 2010
Posts: 15
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| To use an external crystal for this chip, what fuse bits do you have to program? The crystal is 10mHz |
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Posted: Mar 14, 2010 - 06:18 AM |
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Joined: Jul 13, 2008
Posts: 204
Location: Pennsylvania
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If you haven't already, download the datasheet. Look under the "Clock Sources" section for the settings. Then cross reference that to "Fuse Bits" section.
Set "External Crystal/Ceramic Resonator" not "External Clock " BTW. some make that mistake. |
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Self proclaimed Captain Link
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Posted: Mar 16, 2010 - 11:08 PM |
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Joined: Mar 07, 2010
Posts: 15
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I did look at the datasheet, but it only tells you how to set bits 3-1, not bit 0. here is the section i read:
Table 4. Crystal Oscillator Operating Modes
CKSEL3..1 Frequency Range(1) (MHz) C1 and C2
100(2) 0.4 - 0.9 –
101 0.9 - 3.0 12 - 22
110 3.0 - 8.0 12 - 22
111 8.0 - 12 - 22 |
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Posted: Mar 17, 2010 - 12:29 AM |
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Joined: Jul 13, 2008
Posts: 204
Location: Pennsylvania
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bottom of table 4 reads
Quote:
The CKSEL0 Fuse together with the SUT1..0 Fuses select the start-up times as shown
in Table 5.
Table 5 is first thing on the next page and lists settings for CKSEL0 and SUT1..0, which you will also need to set. |
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Posted: Mar 17, 2010 - 02:26 AM |
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Joined: Mar 28, 2001
Posts: 12827
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
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Quote:
I did look at the datasheet, but it only tells you how to set bits 3-1, not bit 0.
I never look at the data sheet for fuse bits, too hard. I use Studio's programming interface which tells me exactly what each setting does in plain Enlgish.
I guess you are not using Windows or Studio or have a non Atmel compatible programmer? |
_________________
John Samperi
Ampertronics Pty. Ltd.
www.ampertronics.com.au
* Electronic Design * Custom Products * Contract Assembly
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Posted: Mar 17, 2010 - 12:58 PM |
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Joined: Feb 19, 2001
Posts: 18830
Location: Wisconsin USA
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Quote:
I did look at the datasheet, but it only tells you how to set bits 3-1, not bit 0. here is the section i read:
Didja read like one sentence below that chart?
Quote:
The CKSEL0 Fuse together with the SUT1..0 Fuses select the start-up times as shown in Table 5.
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