We do not have a specified minimum time timeout interval, but I think that you should be able to set it to 30s without running in to any issues. Generally, I would just test som different values and if you dont see any issues, then you're ok.
What the program is doing in the time of time out? Why the default is 120s？All the steps of DFU is no more than 30S?When I changed the timeout to 30S, could it be possible to trigger a timeout before dfu_timer_restart()?In this case, DFU will always fail.
No, i do not think so since the bootloader is waiting for peer activity, i.e. waiting for the start packet, the init packet or a data packet. And as you say the dfu timer will be reset everytime one of the packets above is received.
