Attiny 25 reset pin used as a PIN Change Int Source

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#1
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Hi all !

I'm trying to make an aplication using Attiny 25 and I have to use the Reset PIN as a Pin Change Int Source 5 . In the datasheet (section 20.5 ) I have read that the RESET pin has to be held down ( logic 0) to write EEPROM and Flash memory ( ISP ) .

Can I use in system programming if a use Reset pin as a PCINT5 ? If not how can I write program to chip ?

Thank's !

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Once you disable the reset pin by programming the RSTDISBL you can no longer use ISP. The only way to undo this is to use high voltage programming.

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Yan1978 wrote:
If not how can I write program to chip ?

Program a bootloader into it prior disabling the reset pin.

Peter

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Thank'a a lot ! I will try to find something else because ISP is most necessary for my project !

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Quote:

I will try to find something else because ISP is most necessary for my project !

It doesn't have to be if you follow Peter's suggestion.

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You could step up to a tiny45/85 to offset the Flash consumed by the bootloader. But you also need some way to interface to some external programmer, maybe the circuit cannot easily accommodate this, but we don't know this :) The lack of an UART makes it more difficult too.

Selecting another AVR, maybe a t24/44/84 which is 14 pins, might be easier after all.