@zpm1066 thank you for the amazing feedback! 😄
zpm1066 Like the majority of the “makers”, nearly all the sensors I use are 3.3V. However, for the longer term, I think it’s worth having a configurable 1.8-3.3V VDDIO if not much additional effort.
It is possible actually with the nPM1300. The only part that wouldn’t work is the onboard NOR flash. It does not support such a wide voltage range. They have 1.8V variants and 3.3V variants. My thoughts would be to go with the 3.3V version and if any flash writes need to occur the buck needs to be placed into 3.3V mode. Testing is still necessary since I’m not sure how the flash would handle 1.8V. If it ends up leaking tons of current that would put the kibosh on it right there.
zpm1066 Are you planning on driving the RP2040 at 3.3V or in addition also thinking of using 1.8V, as RP2040 does support multiple power options?
Right now, thanks to all the feedback thus far, the plan is to run it at 3.3V. It does have a separate VDDIO pin which allows for running the IO at 1.8V. It does require 3.3V for USB (which is critical for this board!) on the other power supply pins no matter what.
zpm1066 Will there be an option to shutdown RP2040 if nRF9161 is in a sleep mode?
Good questions. It’s the reason why I’m asking you guys your preferences on IO voltages. 😇 By default it’s on on a cold boot but then is configurable in software to be shutdown when not in use. Both buck converters actually can be configured in “retention mode” which lowers the rail voltages when in a sleep mode (very neat).
zpm1066 Any plans to bring out any of the GPIOs from the RP2040 to the Feather pins?
No plans since it’s mostly meant to be a programming IC. All the GPIOs are going directly to the nRF9161.
