andy_n

Sure, if I can help. I'm a beginner in Linux but have a lot of experience with uC programming.
I'm always looking for aunt google before I 'engage' forum.
But for beginner, the biggest problem is: how do I ask the question?! 
 
I'm always saying my friends: I can not program, but I can google. 
 
Thank again...

guidol!
 
It is working absolutely perfect.
 
In most programming forums you get arrogantly stupid answers (guys who just want to satisfy quote, who has more answers today).
Here you get the right help. Thank you. 
 
Andy
 
 

more elegant would be to know the right moment - when to start- your service and on what it depends.
 
if your service depends (because of the UDP packet = a full working network) then the following page could have an solution for you:
Systemd: how to make a systemd service start after network fully connected?
 
Also have a look at
How to list all services that start AFTER certain service in systemd
 

on a real PC with debian stretch I got the problem of the missing rc.local
 
With instrustions I did rebuild this as a service, but the service was starting too fast - so I had to put a 
sleep 20
as the first command in beginning of the rc.local
 
Maybe your service will also start with pause of 20 seconds? 
Could be a chance because you did wrote it will start successfully when started from commandline.
#!/bin/sh -e # # rc.local # # This script is executed at the end of each multiuser runlevel. # Make sure that the script will "exit 0" on success or any other # value on error. # # In order to enable or disable this script just change the execution # bits. # # By default this script does nothing. sleep 20 systemctl start Announce.service exit 0  
 

Which patches are you using to enable sf command for SPI?  The mainline Allwinner A10 SPI driver does not work with sun8i.  The only driver I've found to work is this older fork.
fork: https://github.com/StephanvanSchaik/u-boot/tree/sunxi-spi
info: https://linux-sunxi.org/Bootable_SPI_flash#SPI_driver
 
It's been awhile since I've used an official armbian image.  IIRC besides kernel related files, it's just overlays, bootscripts, and dtbs.  Also, a couple of armbian related files that need to be kept if you want the armbian OS scripts to work (armbian-config, etc).