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Topic: Avrdude fuse bits and using a usbtiny as an external clock source (Read 631 times) previous topic - next topic

d4wtty

So I am new to using Avrdude and I was trying to replicate a project where an Attiny85 as a rfid tag, in my case I was trying to replicate my school ID badge to a smaller, portable tag. Here's the project link: http://scanlime.org/2008/09/using-an-avr-as-an-rfid-tag/

The whole thing is way above me, but you can't learn if you don't try I suppose. Point is that I got Avrdude up and running and was figuring out how to program the included source files onto the chip (I'm actually using an Attiny84, but will be getting a couple 85s next week). The source files are a Makefile.txt which I understand needs to be used to compile or something? And a .S file, also not sure what I am exactly supposed to do with it. Anyways in the .S file I was follow the comments trying to understand what I need to do and how to set it up. It mentioned:

"Program the fuses for an external clock with no divider.
*     On the ATtiny85, this means setting lfuse to 0xC0.
*     Note that after you set this fuse, your programmer will
*     need to supply a clock on pin 2 for subsequent programming
*     operations."

So I went ahead and set the lfuse to 0xC0 which I have very little clue as to what that did, but now avrdude doesn't recognize the chip and reports:


avrdude.exe: initialization failed, rc=-1
            Double check connections and try again, or use -F to override
            this check.


avrdude.exe done.  Thank you.

From what I do understand I took away the chips ability to use its own clock to run, and I am supposed to use the programmer as an external clock source; however, I don't know how to do that...

In conclusion, I could use some help understanding what I am supposed to do with the Makefile.txt and .S file as well as either restoring the fuse bits (which from what I have read can be done with a second microcontroller?) or even better using the programmer as an external clock source which I would imagine should be doable. I am using the sparkfun AVR pocket programmer (has a attiny2313 chip on it) which seems to work well with avrdude.

Any guidance would be greatly appreciated, thanks.

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