hoping that this will work, but it didn't.
What else needs to be done in order to make USART1 default serial interface for MCU?
Please give a proper description of the problem. No serial comms is too broad. During upload? At runtime?I'm not familiar with the PB version, but others might be able to point you on the right direction.
Yes, everything works fine with USART0. When I connect serial from CH340 to pins for USART1, there is no serial comms.
When I connect serial from CH340 to pins for USART1...
Do you use an Arduino package which supports the MCU?Which one?
I'm guessing MCU has been setup to have USART0 ready for comms after boot, unlike USART1.
What programmer do you use? Arduino as ISP?
Unfortunately, burning bootloader from IDE never worked for me. I tried burning bootloader directly with avrdude (with Arduino as ISP), but I probably have incorrect settings. Flash went fine, but board does not react to upload requests from usb.
I tried this bootloader:https://github.com/MCUdude/MiniCore/blob/master/avr/bootloaders/optiboot_flash/atmega328pb/1000000L/optiboot_flash_atmega328pb_UART0_9600_1000000L.hex