Arduino for STM32

Hi,

I'm using an NUCLEO F103 board and try to send monitor data over Serial1.

This works in setup:

void setup() {
HardwareSerial Serial1(PA10, PA9);
Serial1.begin(9600);
Serial1.println("Testpoint 1");
......


but I have found no way to use Serial1 in other functions
or globally for ...