user4989: We are so tired and would like to get help with this. We are trying to bootload using the arduino Uno.
We have an atmega 328p smd , that we are trying to bootload. We have connected all the right pins, added to the boards.txt the  "Atmega328 on a breadboard(8mhz internal clock)".
Then I have chosen from the "board" menu, this option (internal clock), and uploaded the program. it worked .
Later, I wanted to try and bootload for external clock so I chose from the boards menu the pro mini with 5v board.(is it wrong?)
Not only that I got an error, now, I can't bootload the internal clock again !!
Why can't we bootload again? Did we damage something? Can it be reset again?
How can you bootload for external 16Mhz ??
error :
avrdude: Yikes!  Invalid device signature.
         Double check connections and try again


user10794: 
Not only that I got an error, now, I can't bootload the internal clock again !

You need an external clock source, such as a crystal and two capacitors. Once you switch the fuses to the external clock it won't work any more unless you have such a clock.
I have a bootloader uploader sketch that also provides a clock signal if you need it.

4989: <p>We are so tired and would like to get help with this. We are trying to bootload using the arduino Uno.</p>

<p>We have an <code>atmega 328p</code> smd , that we are trying to bootload. We have connected all the right pins, added to the boards.txt the  <code>"Atmega328 on a breadboard(8mhz internal clock)"</code>.</p>

<p>Then I have chosen from the "board" menu, this option (internal clock), and uploaded the program. <strong>it worked</strong> .</p>

<p>Later, I wanted to try and bootload for external clock so I chose from the boards menu the <code>pro mini with 5v board.</code>(is it wrong?)</p>

<p>Not only that I got an error, now, <strong>I can't bootload the internal clock again</strong> !!</p>

<p>Why can't we bootload again? Did we damage something? Can it be reset again?
How can you bootload for external 16Mhz ??</p>

<p>error :</p>

<pre><code>avrdude: Yikes!  Invalid device signature.
         Double check connections and try again
</code></pre>
 10794: <blockquote>
  <p>Not only that I got an error, now, I can't bootload the internal clock again !</p>
</blockquote>

<p>You need an external clock source, such as a crystal and two capacitors. Once you switch the fuses to the external clock it won't work any more unless you have such a clock.</p>

<p>I have a <a href="http://www.gammon.com.au/forum/?id=11635" rel="nofollow">bootloader uploader</a> sketch that also provides a clock signal if you need it.</p>
