hi steve

thans a lot for your answers.

the circuit is at 5volt so no problems with brown out.

a question to the oscillator selection : i burned the 4mhz bootloader with HS set as config fuse. as i read in the datasheet, there is a table with testing at 4mhz of both, hs and xt. is this correct to use hs at 4mhz?

thanks again