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the ceramic oscillator
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the ceramic oscillator

by hydro on Sun Jul 29, 2007 9:41 am

hi,
i have trouble finding the needed ZTT-12.00MT ceramic oscillator, can i use a quartz and solder the 30pf capacitors separately?
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by adafruit on Sun Jul 29, 2007 11:42 am

yes, its the same thing

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ceramic versus quartz

by oskay on Tue Jul 31, 2007 4:08 am

You may want to double-check your fuse settings versus those in the data sheet; there are very slightly different settings recommended for ceramic versus quartz.

(It's entirely possible that this is a simple no-fuss substitution. In general, though, you want to think about it before swapping out a crystal for ceramic or vice versa.)

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by adafruit on Tue Jul 31, 2007 4:19 am

i tend to set the fuses to be max wait, but ceramic oscillators and crystals use the same settings. i'm 99% sure its a perfect swap in this case.

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Recovering a 2313 after changing clock source

by zzag on Mon Oct 01, 2007 9:25 pm

Newbie here...
LED Clock project with 2313; USBtiny programmer.
Got it working fine using internal RC.
Added 3.58MHz resonator and changed the fuses to "external crystal 3.0-8.0". The clock is now running at the new frequency, but now I can't program (not programming in circuit). I tried the instruction for fixing fuses:
http://www.ladyada.net/resources/ucannoyances.html#fixing_fuses
with no luck.

Currently, I'm modifying the program on a new chip and then changing fuses to 3.58 clock. Could get expensive fast. Any assistance in recovering the used chips would be greatly appreciated... thanks.
Last edited by zzag on Mon Oct 01, 2007 11:01 pm, edited 1 time in total.
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by adafruit on Mon Oct 01, 2007 9:44 pm

er i dont know what you mean by not programming in circuit
the avr must have a crystal when being programmed!

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by zzag on Mon Oct 01, 2007 9:54 pm

ladyada wrote:er i dont know what you mean by not programming in circuit
the avr must have a crystal when being programmed!


Thanks for the quick reply.
Yes, after sending the question I convinced myself that frequency wasn't the problem.
By not in circuit I meant I'm using a "minimalist board" to program. Do I need to jumper a resonator to the XTAL pins for programming?... with capacitors? and to ground?
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by adafruit on Mon Oct 01, 2007 10:09 pm

yes, like i said, it has to have an oscillator attached. the avr must be able to 'run' to be programmed

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by zzag on Mon Oct 01, 2007 10:17 pm

got it, thanks.
how critical is it that the capacitors be with the resonator during programming?

i suppose in circuit programming (probably not the right words... ISP?) would be the easiest, right? any watchouts for ISP? just power down the circuit, connect to usbtiny, and program?

addendum: i just wired for ISP. let me describe to make sure it's okay: power down, connected usbtiny and the existing program begins. i program while the old program is running. ??

thanks for your time!
Last edited by zzag on Mon Oct 01, 2007 10:27 pm, edited 1 time in total.
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by oskay on Mon Oct 01, 2007 10:27 pm

By not in circuit I meant I'm using a "minimalist board" to program. Do I need to jumper a resonator to the XTAL pins for programming?... with capacitors? and to ground?
The minimalist target boards can only be used (as described on that page) if (1) your chip is already programmed to run on the internal RC oscillator and (2) you are programming the fuses such that it will *still* run on the internal RC oscillator.

(You can of course add a crystal or resonator and caps to the minimal board....)

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by zzag on Mon Oct 01, 2007 10:31 pm

thanks for the reply oskay... i'm slowly getting there.

how critical is it that the capacitors be present during programming (e.g. putting a resonator on the minimalist board)?

thx
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by oskay on Mon Oct 01, 2007 10:50 pm

[quote]how critical is it that the capacitors be present during programming[/quote]
Think of the two capacitors as part of the resonator. Any time that you have a crystal or ceramic resonator, you *need* the capacitors as well. (But, if you don't have the resonator, they won't hurt anything.)

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ISP

by zzag on Tue Oct 02, 2007 12:30 am

is this how ISP is supposed to take place:
    power down the circuit
    connect programmer (usbtiny)
    the existing program begins because usbtiny has applied power
    upload while the old program is running. ??
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by adafruit on Tue Oct 02, 2007 12:53 am

when programming the chip, the core is still running. its just not running your code, its running the 'upload new firmware' program.

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