Arduino Serial Connection via GPIO and Level Shifter

[ChaseCrom]

How can I connect a Pi Zero W to an Arduino (Nano in my case) for serial communication using the GPIO pins? I know I need a level shifter, and I have a 74AHCT125 - Quad Level-Shifter (3V to 5V) but I don't understand what connections need to be made through the shifter and what config changes I need to make on the Pi. Googling and looking around hasn't revealed anything useful. I know USB can be used, and I currently do that for development but I don't have room in the enclosure for a big USB cable and OTG adapter.

[DougieLawson]

What's stopping you from connecting the Arduino's USB to the Raspberry's USB? No level shifting needed for that.

[scotty101]

What's stopping you from connecting the Arduino's USB to the Raspberry's USB? No level shifting needed for that.

I know USB can be used, and I currently do that for development but I don't have room in the enclosure for a big USB cable and OTG adapter.

Seems clear.

[DougieLawson]

What's stopping you from connecting the Arduino's USB to the Raspberry's USB? No level shifting needed for that.

I know USB can be used, and I currently do that for development but I don't have room in the enclosure for a big USB cable and OTG adapter.

Seems clear.

Get a craft knife and trim the USB plugs to fit. Get a dremel and trim the case to fit. That's going to be easier than trying to reliably connect more than one GPIO with a voltage shifter.

[penguintutor]

I believe that chip only works one-way, but for serial you will need a bidirectional level-shifter

The following from Adafruit sounds like it should work

https://www.adafruit.com/product/757

Here's a guide to configuring serial on the Raspberry Pi.

https://elinux.org/RPi_Serial_Connection

[ChaseCrom]

What's stopping you from connecting the Arduino's USB to the Raspberry's USB? No level shifting needed for that.

I know USB can be used, and I currently do that for development but I don't have room in the enclosure for a big USB cable and OTG adapter.

Seems clear.

Get a craft knife and trim the USB plugs to fit. Get a dremel and trim the case to fit. That's going to be easier than trying to reliably connect more than one GPIO with a voltage shifter.

It's not that simple. Part of the appeal of the Zero W is that it's small. A USB OTG adapter, even one of the tiny ones, plus even a small USB cable takes up a lot of room in any kind of an enclosure. I'm 3D Printing a custom enclosure, so modifying the enclosure isn't the primary issue; the physical form factor I need is the issue.

[ChaseCrom]

I believe that chip only works one-way, but for serial you will need a bidirectional level-shifter

The following from Adafruit sounds like it should work

https://www.adafruit.com/product/757

Here's a guide to configuring serial on the Raspberry Pi.

https://elinux.org/RPi_Serial_Connection

I experimented around a little and you're correct. I wound up getting the Sparkfun Bi-Directional Level Shifter - same board as you linked, just with a red PCB from Sparkfun. Adafruit isn't currently shipping orders because they've shifted to helping COVID mitigation efforts. The beauty of living in Colorado is that Sparkfun orders are always basically overnight.
https://www.sparkfun.com/products/12009