Hello, sorry for the delayed response.
Were using the OrangePi3 for some reason: cheapness and features, i've bought a small bunch of them for developement purposes in China.
Dear Igor my answer regarding the missing wlan meant the Olimex Lime boards. They seem to lack wlan. The orangepi3s not.
And regarding the buster, bionic etc. issue. We used the distributions delivered by Orange Pi in the first place. I tried first their debian server version which run into some heat issues, after that i red that there are debian issues with the Thermal mangement on the h6 (or h5) so i tried to avoid debian versions. The ubuntu versions worked but they totally lack configuration tools. And the Leds during the bootup process behave different. the debians went green after successful bootup, the ubuntu stays red.
After some research i found armbian where i choosed the ubuntu version for the same reasons.
The led sequence is also important because we need to signalise the bootup und the successful communication with the two serial devices after bootup. Which is not a problem but i would prefer the ubuntu always-red-version until we take control and talk to the devices.
Thats are the reasons why i'm sticking to bionic.
Dear Martin Mayotte
this is the result of dmesg |grep tty after adding your suggested lines to rc.local on my OrangePi3
[ 2.079931] printk: console [ttyS0] enabled
[ 2.101376] 5000400.serial: ttyS1 at MMIO 0x5000400 (irq = 20, base_baud = 1500000) is a 16550A
[ 3.015818] 5000c00.serial: ttyS3 at MMIO 0x5000c00 (irq = 21, base_baud = 1500000) is a 16550A
[ 16.846519] 7080000.serial: ttyS2 at MMIO 0x7080000 (irq = 243, base_baud = 1500000) is a 16550A
it seems that the S-UART got ttyS2, could this change in future or is it sure that i will always be ttyS2 also on other devices . (if there are no changes in hardware of course)
Somebody told to me that a S-UART is also or mostly called USART and also RUART is this correct?
Or are there some minor differences? Googleing on this is extremely inefficent.
Because of some additional needed electronics its a little bit tricky just to put the interface to the other pins so i have one further question.
Is a S-Uart capable of behaving asyncronous as a normal uart or are there some limitations. I couldnt find documentation on S-UARTS.
I have to use it in the range of 9600 to 115200 bps on a normal serial connection.
Many thanks.