Let's say I have a GPIO input that I want to drive high - is it 1.8v or 3.3? Assume it is 3.3v correct, I haven't found it explicitly stated anywhere.
It'll be in the TI doc.
Or web search on something obvious like
Looking at the the AM3352 SOM Rev C schematic all six of the AM3352 VDDSHV1 to VDDSHV6 "Supply voltage range for the dual-voltage IO domain" are connected to 3.3V.
This means all GPIOs use 3.3V signaling.
Funny enough, I *did* have the mental capacity to google the datasheet! I'll admit I did not read every word of it but from what I can tell, the TI datasheet actually *does not* specify an absolute voltage but a range relative to the supply cell voltage (suggesting it could be *either* 3v3 or 1.8v depending on configuration.) Unfortunately neither the Olimex user guide nor the GPIO pinout doc (https://www.olimex.com/Products/SOM/AM3352/AM3352-SOM/resources/AM3352_SOM_GPIOs.pdf) actually call out the exact value. But by finding those signals on the SOM schematic I believe you are correct. Thanks again!