Pi Hat eeprom chip needed?

[lilaperua34]

I have a raspi hat (rak2245) that has 2 versions: a pi-hat version that has a 40 pin-header on it for raspberry pi's , but also a smaller stamp edition. It uses spi and uart to communicate with the pi. I have it running without issues on my orange pi zero, even though the pinheader is a little too large. And via a breadboard I can access all pins just fine. But since I am making my own PCB anyway, I am interested in using the stamp version.

The only difference between the stamp and the pi-hat version (aside from the form-factor and pin-out) is that the pi-hat version has an additional eeprom chip to tell the rapsberry pi about the function of the pins apparently. Now I wonder if that chip is just a convenience or if I can actually do without it. I am comfortable making my own device tree overlay files to indicate pin functions. I've done it with spi before to add additional CS pins on the orange pi zero. So my question is, would that likely be enough to get the stamp version running, or would leaving out the eeprom chip likely make it not work (without serious driver development work)?

 

Cheers.