While building my Uzebox, I ran into some trouble. When I tested the sound it was *terrible*. I tried changing some Oscillator fuse bits and it seemed to improve a little. Then I got too ambitious changing fuse bits and bricked my chip.
I probably could have just attached an oscillator but this was more fun! I wanted to build something that used HVP but all the plans I found relied on another chip to work. I wanted my chip fixed without buying another one! So, I followed the datasheet and invented this very specific device that allowed me to reset the fuse bits, without running any software. I thought some of you might appreciate it.
The process is difficult; it took me three tries to get right. I wasn't sure if the LED (that indicates the write is happening) would be on long enough for me to see it, so I got my eye right up next to it and almost blinded myself when it worked! Still, it was SO rewarding to see that little light. This is actually one of the first circuits I've designed.
Here's the device:
Oh yeah - what turned out to be wrong with my Uzebox? I didn't realize all the files I was flashing were from a buggy kernel I'd hacked.
Silly Invention: Hardware-only ATmega defuser
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- Posts: 65
- Joined: Tue Dec 08, 2009 7:44 pm
Re: Silly Invention: Hardware-only ATmega defuser
An odd looking contraption, but if it works! Do you have the schematic, I'm curious to see how it works.
-Uze
-Uze
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- Posts: 65
- Joined: Tue Dec 08, 2009 7:44 pm
Re: Silly Invention: Hardware-only ATmega defuser
Eh, I never made a schematic, which might account for why it took me three days to build it.
I'll have to make one some day - I'm still starting out with electronics so I haven't made many.
I can tell you that it's mostly pull-up resistors and some pull-down resistors and switches, jumpers or buttons that short the logic to the non-pulled state. There's also a current-limiter, bypass capacitor and LED / resistor.
For instance, XTAL1 is normally pulled low, but when you press a button it pulses high. You hook up power, pulse XTAL1 6 times and remove a jumper that was preventing 12V from going to reset. this is how the device first enters HVP mode.
...Yeah, it's crazy; I'm going to have to make a schematic...
I'll have to make one some day - I'm still starting out with electronics so I haven't made many.
I can tell you that it's mostly pull-up resistors and some pull-down resistors and switches, jumpers or buttons that short the logic to the non-pulled state. There's also a current-limiter, bypass capacitor and LED / resistor.
For instance, XTAL1 is normally pulled low, but when you press a button it pulses high. You hook up power, pulse XTAL1 6 times and remove a jumper that was preventing 12V from going to reset. this is how the device first enters HVP mode.
...Yeah, it's crazy; I'm going to have to make a schematic...