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Topic: Arduino bootloader on atmega8 default fuse settings?? (Read 3359 times) previous topic - next topic


Hello everyone,
I am making a segway clone for my friends college project, and I implemented a minimal arduino circuitry on a custom pcb. I do not own an avr programmer and didnot have much success with the parallel programmer so I gave my atmega8 chip and the hex file to a friend and asked him to get it burnt[if thats the correct term]. Everything was perfect but he forgot to burn the fuses!!! I was wondering if there will be any problem running arduino8.hex bootloader on atmega8 with default fuse settings.
[Its kinda pain in behind to get the chip burnt again, thats why I just want it the way it already is]
Also, what is the default pwm frequency? Will incorrect fuses affect it?

Thank you

Coding Badly

I was wondering if there will be any problem running arduino8.hex bootloader on atmega8 with default fuse settings.

What do you mean by "default fuse settings"?  Are you saying the ATmega8 fuses have not been changed from the "factory settings"?




Mar 04, 2011, 03:45 pm Last Edit: Mar 04, 2011, 03:47 pm by alparent Reason: 1
This is not really a answer to your question........but....

Do you have an Arduino board? If so....you can use that as a programmer.

And we can show you how to do it easily.


Yes, the factory settings.

As I've been lead to believe, factory default fuse settings results in the chip running on internal R/C 1 Mhz clock speed, is that exceptable for your application? I suspect not.



@ alparent
I have 2 unos and a mega 2560, afaik unos cant be used, and theres something wrong with my mega, when I connect it to my computer, the software cannot see it, but the serial monitor can!

@ retrolefty
Default is 1Mhz?? I thought it was 4!

I have a ftdi breakout board and a buspirate! I've already borked an atmega8 using buspirate [the sparkfun one btw]. You guys had any success with ftdi, as described on ladyada.net ?




Ok let's just start over.

First you need a board with a working atmega.
Then there are 2 steps. 1- Put the boot loader on the chip (this might be done already) 2. Put the sketch on the chip.

To do the first part, load the Use Arduino as ISP sketch to the chip on the board.
Make sure you ave selected the right board and the right port.
Then connect you breadboard like this (bottom secion of this page) Circuit (targeting an AVR on a breadboard) http://arduino.cc/en/Tutorial/ArduinoISP
Like I said it only worked if I used an external clock. (I have the Uno board, with optiboot)

Then use the burn bootloader with arduino as ISP.

Now your new chip as a bootloader!

Then remove the chip from your board.

You could just pop the new chip on the board and program any sketch you would like on it.

But is you want leave the chip on the breadboard and load  a sketch on in.........do this.....

Disconnect wires to header pin 10,11,12,13 and connect pins rx and tx the the rx and tx pins on the atmega on the breadboard. Like this
http://arduino.cc/en/Tutorial/ArduinoToBreadboard  Uploading Using an Arduino Board

Then add a wire from the board socket pin 1 (reset) to the breadboard chip pin 1 (reset)

Then load the sketch you want to the chip on the breadboard.

Remember never to change the board selection............but like I said it only worked with an external clock.

All this with my Uno board.

So now you can load the bootloader and sketches yourself.


Nope! no success! uno hates me!
Btw how do I know if I have optiboot?



The atmega328p that came with your Uno as the optiboot.

Can you describe in details what you are doing?
Steps, selections, etc 


Like I said it only worked if I used an external clock.

does crystal oscillator count as an external clock?
and im using 33pf caps[with 16Mhz crystal], is that the reason my chip misbehaved last time?


Yes, external oscillator is a better term.

As for the caps value, I think not using the right values will change the actual frequency of the oscillator.

Is that what's causing your problems.....? Don't know?

But I would start by doing everything as instructions says so you eliminate any possible problems.

(I use a 16mhz 3 pin resonator, It as the caps integrated.)

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