in the manual it says that VDDIO_EXT can be connected to external 1.8v supply but i think i damaged the chip by doing that. What is the correct way of setting the DIO to 1.8v logic level?
@arduinonano33ble, your topic has been moved to a more suitable location on the forum. I unfortunately don't have an answer.
I know you have the unit in front of you but my eyes cannot see it, they are tired and old. Please post a link to what we are talking about that includes technical information. One of the items this looks like is a bluetooth module but then which one/configuratioj?
This is about the Arduino Nicla Sense ME board.
The full datasheet referenced above, along with schematics and pinout is available here:
https://docs.arduino.cc/hardware/nicla-sense-me#resources
As the datasheet says:
VDDIO_EXT is software programmable.
And the pinout diagram says:
To power the Nicla Sense ME using VDDIO_EXT, disable the LS/LDO pin of BQ25120AYFPR
I see that the (mostly) undocumented "Nicla_System" library has a disableLDO function.
So putting all this together, it seems the move would be to call nicla::disableLDO() to disable the LDO on the Nicla Sense ME's BQ25120A power management chip when providing the desired voltage level via the VDDIO_EXT pin on the header.
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I have no experience with this but your solution sounds good to me, give it a try.
"Note the LS/LDO output needs to be disabled first before setting a
new LDO value or before switching between LDO and LS."
exactly, so this is the LDO it is using. To set it to 1.8v, first the nicla::disableLDO(); has to be called, then the correct voltage can be configured by calling the nicla::enable1V8LDO();
btw i tried just disabling the LDO and supplying the voltage externally but it didn't work. The above is the software solution to it;
Thanks for the help 
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You are welcome. I'm glad you got it working. Thanks for taking the time to share your findings!
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