Soldering directly to ATMega4809 pins on Nano Every for more GPIO?

Projects General Guidance
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I note that the ATMega4809 on the Nano Every has 48 pins. Is it possible that soldering directly to the pins, a very fine piece of enamelled wire, with a fine tip and a microscope, one could get additional GPIO pins? Or is the Arduino firmware not prepared to use those b-b-b-b-bonus pins?

2

Not aware of the pcf8575...??
Might be a lot easier and safer.

3

Thanks for the suggestion. I do know about GPIO expanders but where's the sense of pride and accomplishment in that?

4

I would simply hold a probe on one and see if you can control it. If no probe, use an LED with resistor. If that works you should be able to bring them to a more useful termination.

5

See the data sheet! The 4809 in 48 pin case has 41 GPIO pins on 6 ports. 16 pins also can be used as ADC inputs.

For use of the additional pins you may have to edit the controller files in Arduino\hardware\arduino\avr tree, starting with boards.txt and pin definitions in a new pins_arduino.h. It may be done already if you can find there already Every related directory or files.

6

You could use the MegaCoreX Core
I'm pretty sure that their "48pin Standard" pinout option supports all of the pins.
(the other pin numbers might change designation, though, so creating your own "variant" might make more sense.)

Very fine wires soldered to bare pins doesn't really sound very workable.
You could design your own PCB.
Or image

Or you could get something like A Microchip ATmega4809 Curiosity Nano

Note that the "41 IOs" would require repurposing the signals that normally implement the crystal oscillator, Vref, and Reset. so 37 is a more realistic maximum. On an Uno-like design you can easily do the normal 20 IO, plus dedicated LED, I2C (2), SPI (3), and Serial (2) for 28 easily accessible IO.

7

Well, you probably wouldn't be here asking for one.

8

From what I can see, the "Nano Every" pinout of MegaCoreX maps all 41 I/O pins, with all the ones that are broken out on the Every using their normal pin numbers, but also pin numbers for all the rest:
https://github.com/MCUdude/MegaCoreX/blob/master/megaavr/variants/nano-every/pins_arduino.h

I agree with westfw that the Curiosity Nano or a DIY board will be more practical, but if you are only looking for an interesting challenge then it might be fun to see what you can accomplish with the Every.

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