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Topic: [solved] Changing CPU speed & boards.txt (Read 13066 times) previous topic - next topic


In my experience, once you switch the fuse settings to an external crystal, if there is a problem with the external crystal, then the processor will not communicate through an ICSP.  Once the crystal issue was resolved everything worked.  Your experience sounds similar to mine but not identical.

Do you have anything connected to the board?

I did have, but I took it it all out to go 'back to basics'. I connected the 'L' LED, but that's all. (Aside from the crystal, of course)

Your point about the crystal is intersting. After I'd burnt the bootloader, I could upload Blink fine the first time. Then I changed the delay to 100ms (so that it would be obvious the program had definitely uploaded), and sometimes it would upload, sometimes it would give the verification error. I was never able to upload more than 2 programs without having to re-burn the bootloader.

It would be simpler if I were able to use the FT232 breakout I have... My first thought was that it's a problem with the timings, as maybe they're never 'syncing'?

I'll try another few crystals and double check the crystal setup and report back.

Thanks for the advice so far.

Coding Badly

By "crystal" do you mean "crystal and capacitors"?


By "crystal" do you mean "crystal and capacitors"?

I do!

So after all that, and all your help, it worked.

When uploading the bootloader it gave a verification error, yet I can upload programs absolutely fine.

Having uploaded and tested them, I can confirm that all functions to do with timing work fine. All I had to change was the cpu speed and upload speed, as suggested.

I've no idea why it wasn't working before, but it does now!

Thanks for all your help.

Coding Badly

I'm glad to know you have it working and thank you for the follow-up.



Thanks alot for your post and really help the people like us.

I am trying to burn bootloader in ATMega2560 8au with 8MHZ crystal but instead of Arduino bootloader I am planning to use Gammons Bootloader.

As per your suggestion we need not to change any thing in bootloader so i think if i make change in board.txt will be enough.

Please correct me if I am wrong.


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