The current advice is that one true HAT and one true HAT+ can be stacked provided there are no pin conflicts and no I2C address conflicts.
A true HAT[+] has an on board EEPROM containing configuration data. Many third party devices that look like HATs (and are advertised as such) aren't because they lack the EEPROM.
Devices without the ID EEPROM can very likely be stacked provided there are no pin or address conflicts. Same applies to devices with the EEPROM if you're willing to disable auto configuration probing and load the config manually. However such stacking is not, AFAIK, officially supported.
As for your ribbon cable question, that depends on the cable and the physical connectors on the HATs. What I'd expect most problems with is getting a reliable supply from the battery to the Pi and screen over it. Most ribbon cables I've seen don't use very thick wires.
And to preempt your next question "how do I know if there's a conflict?": you ask the board's manufacturer.
A true HAT[+] has an on board EEPROM containing configuration data. Many third party devices that look like HATs (and are advertised as such) aren't because they lack the EEPROM.
Devices without the ID EEPROM can very likely be stacked provided there are no pin or address conflicts. Same applies to devices with the EEPROM if you're willing to disable auto configuration probing and load the config manually. However such stacking is not, AFAIK, officially supported.
As for your ribbon cable question, that depends on the cable and the physical connectors on the HATs. What I'd expect most problems with is getting a reliable supply from the battery to the Pi and screen over it. Most ribbon cables I've seen don't use very thick wires.
And to preempt your next question "how do I know if there's a conflict?": you ask the board's manufacturer.
Statistics: Posted by thagrol — Sat May 17, 2025 9:44 pm