Re: Inverting RST pin (using configuration file) not working on Raspberry Pi?

[Gavin Dean]

Completely agree with the HW solutions here.  One of the 74x04 inverters will work, depending on the specifics of your setup.

https://www.ti.com/lit/ds/symlink/sn74ls04.pdf?ts=1622518492304&ref_url=https%253A%252F%252Fen.wikipedia.org%252F

On Tue, 1 Jun 2021 at 13:10, Konrad Rosenbaum <konrad@silmor.de> wrote:

Hi,

On 01/06/2021 19:59, John Klimek wrote:
> I'm using avrdude (v6.3-20171130) on my Raspberry Pi, but I need the
> RST pin to be inverted because I'm using an NPN transistor to protect
> the RPi from my Arduino's 5V power.

A completely dumb idea: add another NPN transistor to invert the pin
again - then there is no need to mess about with the pin and syntax.

You could also use a logic level change circuit, like the common BSS138
based circuits you get relatively cheap on eBay or Amazon.

You also need to protect the other lines (MISO, MOSI, ...).

Alternatively you could supply the Arduino from a 3.3V supply via the
6pin programming port - the AVR chip on it can usually work with this
without much trouble (even though the datasheet says it needs 5V at 16MHz).


     Konrad