ATTiny44A, RSTDISBL fuse and serial programming

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Being somewhat short of I/O pins of an ATTiny44A, I'm considering setting the RSTDISBL fuse to use Port B3 as a general I/O pin. Now, before doing so, I'd like to know if this will inhibit serial programming of the chip, since pulling RESET (alternate function of B3) low is necessary to initiate serial programming. Am I missing something here?

Einstein was right: "Two things are unlimited: the universe and the human stupidity. But i'm not quite sure about the former..."

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I'd like to know if this will inhibit serial programming of the chip,

Yes it will stop normal ISP programming, if the chips is in a DIP package then you could use HVPP programming on something like a STK500 or STK600.

 

Otherwise you need a programmer capable of doing "High-voltage Serial Programming"  SEE 21.7 High-voltage Serial Programming in the data sheet
 

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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The other alternative is to put a bootloader into the chip before you "switch off" ISP. That way you can continue to reprogram it without the need for a high voltage programmer. You won't be able to change fuses though so you must make sure they are set as you want them before you turn stuff off.

 

Of course the other way to do this is to actually develop using a multi-pin AVR in place of the tiny44 then just port the complete solution to the tiny just before you switch off the ability to reprogram it.