My employer currently uses the PicoCOMA9 for one of its equipment ( https://www.wika.com.br/ga11_pt_br.WIKA) and we are required to do some firmware update once in a while. The main issue with that is that some USB Sticks/Flash Drives work during its boot up process allowing the update to happen, but most USB sticks don't, and I couldn't find a general rule to identify which ones would and wouldn't work.
Is there any exact specification for the usb sticks in order to be compatible with the PicoCOMA9 boot process? It is running on Linux, but I don't have much information about it.
The same USB sticks that do not work for firmware upgrade, do work afterwards, for example, while exporting the collected data from the system as a backup drive.