Combining HATs / addons

[fredrlw]

I was wondering if it is possible to stack several diffrent HATs / addons on the Pi ?

For example a GPS HAT and a Servo HAT for a Drone, can you just solder them on top of eachother with the GPIO pins?

[karrika]

Short answer no. The HAT specification says that you can have one HAT card with id-eeprom. But you could stack non-HAT cards if the pins don't conflict.

[mikronauts]

You have to look at the documentation for each add-on board, and see what gpio pins they use.

Only +5v, +3.3v, GND, and I2C pins may be shared without conflict (as long as there are no I2C addressing conflicts)

You may also have problems with hats having an ID eeprom, at the same address, not initializing properly.

There are some add-on cards that are designed to stack (like Mikronauts products), but even in those cases, you need to make sure there are no GPIO conflicts.

I was wondering if it is possible to stack several diffrent HATs / addons on the Pi ?

For example a GPS HAT and a Servo HAT for a Drone, can you just solder them on top of eachother with the GPIO pins?