Serial Port on Raspberry Pi 3 B+

similar to the issues that came along with switching to RPi3 (from RPi2) there are again issues with the latest model of RPi (3B+).

Currently I am not able to get my Raspberry Pi booting with and attached a serial device on the GPIO pins (as they wer working flawlessly with RPi 3).
I modified config.txt and added:
enable_uart=1 and core_freq=250
but Raspberry Pi won’t boot at all (no green light flashing at any time, just permanent red light).

Any ideas?

Thank you very much!
Best regards

Hi. What OS version are you trying to boot your RPI3 B+ with?

I’m using the latest resinOS 2.12.5.

issue is resolved. Out of nothing it started to work, so I guess it was probably a hardware issue (not properly attached the module onto the GPIO pins)…

Sorry for the confusion,