Serial1.setup hangs IDE cmd line with Pico

This works on original Espruion but hangs IDE cmd line window on Pico 1v75 & 1v77
Do I need to do something different on Pico?

print("start");
Serial1.setup(9600);
print("end");

Change to serial 2 works fine

Serial2.setup(9600);

Thanks

Does it work if you explicitly set the pins up?

My guess is it's defaulting to the lowest numbered pins with serial - A9/10, but one of those is USB vsense, which could maybe cause the chip problems when configured as an output but also fed with 5v.

If that's the case I can just disable serial1 using A9 in the next firmware

-- Does it work if you explicitly set the pins up?
No :( just calling Serial1.setup causes the issue.

Also can I clarify my understanding Serailx x is an instance of serial class/obj.
By defining the correct rx/rx pins in .setup I can use usart1 (rx:b7 , tx:b6) or usart2 (rx:a3 , tx:a2) ?
So this will work

// usart1 via serial2
Serial2.setup(57600,{rx:b7,tx:b6,bytesize:8,parity:none,stopbits:1});

No :( just calling Serial1.setup causes the issue.

Try this:

print("start"); Serial1.setup(9600, {rx:B7,tx:B6}); print("end");

It works for me. I think you weren't capitalising the pin names so they were just being set to undefined?

By defining the correct rx/rx pins in .setup I can use usart1 (rx:b7 , tx:b6) or usart2 (rx:a3 , tx:a2) ?

Afraid not - SerialX is an instance of the Serial class, but it is tied to a specific hardware peripheral, so to use USART1 you need Serial1 and so on...

@Gordon thanks as always now cooking on gas!