Thank you for your answer!you are right!
We need to have the uart working , a program compiled in c working ,and wifi and dhcp server ...for now i think all we need is this.
We want to develop a datalogger which will read the data from an external micro and display it over a webserver over wifi.
My compiled openwrt-ar71xx-generic-onion-omega-squashfs-factory.bin is 16.3 Mb is it normal? i remove all what i can...but the Mbytes are the same of the last image from the site ...
Is the .bin format a standard size ? i have different other files in the bin folder inside the compiled image..
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-onion-omega-squashfs-sysupgrade.bin
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-root.squashfs
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-root.squashfs-64k
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-uImage-gzip.bin
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-uImage-lzma.bin
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-vmlinux.bin
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-vmlinux.gz
/home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-vmlinux.lzma

the one i tried is /home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-onion-omega-squashfs-factory.bin that is 16,3 Mb

is /home/marco/opewrt/onion/from_source/openwrt/bin/ar71xx/openwrt-ar71xx-generic-onion-omega-squashfs-sysupgrade.bin that is 1,9 Mb usable as well?

Thank you.

Hello everyone some one know if there is a way to reduce the boot time to less than 10 seconds?
I tried building the image from source but the resulting boot time was 14-15 seconds (the original one was about 18 seconds)
For our project we need onion to boots and be ready in less than 10 seconds after the power supply is given.
Thank you for the help!
Marco