Automatic PPP configuration of the serial port

Hi all.
I'm working with Nanopc-t2 device which has a built-in Android OS. I need to connect the UART device to the board and establish the PPP connection over it. I've already done the task with serial port and got the working port ttyAMA4. Then I can manually start the pppd script to establish the connection.
I'm interesting in such thing: can pppd service be called automatically when the serial port is available? I know that in Linux OS it's can be done by creating the file like "/etc/ppp/option.ttySX" where all ppp options are described. I've created the file "/etc/ppp/option.ttyAMA4" but it's not working.

Thanks.