Dear Nordic team,
I have a complex question. In my project I use components which operate at 2.25V as well as they expect 2.25V logic levels.
My idea is to use nrf52840 chip and run it natively with 2.25V, so the logic level of the chip is also 2.25V, which will let me get rid of the logic level shifters components.
I was able to connect the PPK2 in source mode to the External power supply of my nrf52840DK, supply 2.25V via the power profiler application and see, that the code executing on the nrf52840DK indeed sends out 2.25V as a logic HIGH to the GPIOS. However, as soon as I've connected the nrf52840DK to the computer with the USB cable, the logic level changed to 3.3V. I assume the USB took over. Therefore, my first question:
- Is it possible to supply nrf52840DK with the external power and stick to that external voltage as the logic level, but at the same time still being able to utilise USB for debugging purposes in nrf Connect SDK. I've read there's a way to write to registers, but I am wondering if there's a hardware way to do this, without any programming of the chip.
The next question is related to the stage of programming the final device with the nrf52840 chip on it. If I am able to run the whole system with 2.25V and the same logic level, once I decide to program my external nrf52840 chip via SWD using nrf52840DK as a programming board, will the DK be able to do it with 2.25V logic? Or will it switch to 3.3V and then the whole custom device will maintain the 3.3V while the programmer runs? This is critical, since 3.3V will damage the other components in the project which need no more than 2.25V to operate.
