We have all of our GPIO configured to run at 1.8V, but it looks like the boot ROM has the UARTs configured for 3.3V? When the DA14681 part is reset, and it is looking for sources to boot from, we see 3.3V pulses on the P1.3 UART TX line. (Scope capture attached.) We have devices connected to these pins that are running off of a 1.8V supply, and are not 3.3V tolerant. We are not running the production boot flow yet, as we are still under development. We are booting from a QSPI flash part. Two questions:
Is there a way to fix this now, so that we never see these 3.3V pulses?
When we get to production, will these pulses never happen because we will be booting from QSPI?