Fuse restore ATtiny11, ATtiny12, ATtiny13, ATtiny25, ATtiny45, ATtiny85.
Using as many I/O lines as possible on a small AVR like the ATtiny45 / ATtiny85 you need to fuse the RSTDISBL fuse bit. That bit will enable the normal Reset input pin as a (almost) normal I/O line, PB5. But there is a problem doing that, the in circuit programming (ISP) will not be possible any more after burning the fuse. So it is the last thing to do, if you want to reprogram the chip again!!!
To reprogram that fuse bit a special high voltage (12V) AVR programmer is needed, I do not own that kind of programmer. So I found the page of Dick Cappel to do the same for the ATtiny12 chip. I build that one and changed the source for use by the ATtiny45 / ATtiny85. For my wire-print I changed the I/O lines from the ATtiny2313 host cpu and added 3 input to select the default fuse bits, my own most used fuse bits open and closed fuse bits. I also changed the AT90S1200A to the (more recent chip) ATtiny2313 that also need no external crystal (and I have some of the cpu's at home). For the fuse bits I use lFuse = 0x64, hFuse = 0xDF and eFuse=0xFF (it is the chip default, 8MHz internal RC + divide by 8).
For the 12V power adjustment (only a 9V battery is needed) please check the page of Dick Cappel, you only will have to do that once. NOTE that in steps 3 and 8, you must bridge pins 18 and 20, NOT pins 11 and 20 (because we are using an different pin-layout).
Not all the models are tested in real life yet, please report if one of them is working for you (Thanks!!).
If you need some other AVR model, I can check if it easily can be added to the code. If you did add a other type, and are willing to share the code, please send me a email.
The following models are supported.
ATtiny13, ATtiny25, ATtiny45, ATtiny85
ATtiny11, ATtiny12 Not confirmed!
X = Connected to ground - = Not connected
|Lock the chip.|
|Unlock the chip.|
|Erase and factory default fuse bit settings.|
Download the AVRStudio project Fuse Restore ATtiny45 V0.3.zip.
Download the C source FuseRestore.c.
Download the ATtiny2313 hex file FuseRestore_ATtiny2313_V0.3.hex.
Download the AT90s2313 hex file FuseRestore_AT90s2313_V0.3.hex, you need to add a crystal to the cpu!
Ken, K9FV Phil Dusan YT1DL David, the FlashyLight blog.If you have a picture of your own build, and want to show it, mail the picture to me and I will put it on the website.
|File last modified on Saturday, 19-Jan-2013 21:55:20 CET||