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Topic: arduino with internal oscillator on 1Mhz (Read 40 times) previous topic - next topic

acgourley

Hmm, interesting. I don't have any special hardware to burn a bootloader so I guess this project will have to go on hold. Something I'll circle back to as I am interested in revising this project to be low power.

Marvin Martian

I've got a stand alone battery prowered 328 project that runs off 3 AAs - it "works ok" but reading here is sounds like I'm on the edge of it running successfully at 16MHz.

I was considering dropping the crystal down to 8MHz to give me a wider power margin - Comms is not an issue as I'm programming the 328 in an Arduino then taking it out and dropping it in my PCB.

But it sounds like just changing the crystal won't work either and it will require a software tweak too - is that correct?

Cheers

mungbean

As I understand it, clock speed is hard-coded into the bootloader, so changing the crystal isn't enough to change the speed.  You would need to program a new bootloader in as well.

Given what we've been discussing about clock dividers above, it would seem that changing the crystal isn't actually necessary - a bootloader that sets the clock divider would suffice.

Marvin Martian

But without the capability to reprogram the bootloader that's going to be a bit awkward. Ho hum.

Cheers

mungbean

If you have a windows machine and can solder a 4-way header onto your standard-format arduino (diecimila, duemilanova etc) then you can reprogram the bootloader:

http://www.geocities.jp/arduino_diecimila/bootloader/bitbang_w_ide_en.html

When I last tried with a mac (July 09) it wasn't possible using the mac's FTDI driver.  Instead I used Windows running under parallels.

See also this post/thread: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1258854659/7#7

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