I think you missing my question... (sorry) What I am asking is if I can make a BOARD wich have an SD attached with a .HEX on it, (not an isp, computer, etc) to act as a STANDALONE programmer for other boards, just via serial protocol... Ex I have the NANO with CARD, going to my neighbor, plug a Rx-Tx to his UNO (for ex,) and by hitting a button on my "DEVICE" just upload that .HEX to my neighbor's board...
The IDE talks to the boot loader via a serial protocol. This need to be replicated. I don't know if the IDE does this directly or via Avrdude. I thought Avrdude only did ISP, parallel and HV serial (not boot loader).
Other than occasional ISP use I just use the boot loader upload and don't worry about how it works.
That is especially what I want to know... HOW they communicate, I am plenty of knowledge to use avrdude, but I wish to pass to simply what I need, so get a NANO with me and program an another.... WITHOUT a laptop or desk computer... just a "STICK" dedicated to do the job
..and PLEASE, DO NOT make personal talkshows in the topic, I don/t wish do deviate my topic on discussions between people, hope you get it... personal stuff in private please !
That is fully described in the avrdude documentation. Plenty of literature from Atmel (now Microchip), too. The protocol has been standard for a couple of decades.
(What you want to do is possible. I don' t think it has been done yet, mostly because once you have an Arduino-class device "local" to the target to be programmed, it's just as easy (and more powerful) to use the real ISP programming protocol.
The bootloader(s) use the same communications protocol as various device programmers; avrdude doesn't actually know that it's talking to a bootloader.
"Several Dozen" was an understatement, BTW. I counted, and there are 113 options for the "-c" avrdude option. (some are similar to one another, like the same comm protocol with a different USB id.)