I’ll try to be short, im using an bananapi zero m2 hooked up to a normal genuino arduino uno from Uart3 rx to arduino tx port ( i havent found it but is uart3 pin 5v or 3.3v?). The OS thats etched on the banana pi zero is Arch linux. The ttyS0 and ttyACM0(through usb directly to arduino) work just fine (in 38400 clock 5v). But im assuming that the ttyS3 and others are deactivated. How would i go about to configure it? I hooked the gnd to pin 6 and arduinos tx to pin 10
The image uses uboot, which i havent managed to manually compile so i had to use an old image.
When i try to use the ttyS2-S5 they reply with a Input/Output error on the console