@mfalkvidd The Arduino builder generates two .hex files, one of which contains the bootloader as specified in boards.txt. Depending on the flashing settings you may burn the sketch only or the sketch + bootloader, however, the bootloader is not needed for ISP programming.

@encrypt Ok, this explains your issue: programming via ISP will do a chip erase and hence the EESAVE fuse setting is critical for e2p persistance. The most common use case is programming via serial bootloader (e.g. optiboot, atmegaboot, etc.) which only does page erases and leaves the rest untouched. To answer your question: If you're using an ISP programmer you do not need a bootloader.

@encrypt I may have an idea what's going on here: Are you programming a new sketch to your barebone AT328p via ArduinoISP or any other means of serial (=SPI) programming? Programming via bootloader (ATmegaboot or optiboot) requires a FTDI adapter and will only do page erases while leaving the eeprom untouched.

@anticimex @Encrypt That's a bit odd and certainly specific to the bootloader you're using (ATmegaBoot): AVRdude does (at least with optiboot) a page erase (vs. chip erase where EESAVE has an effect). I do not have the EESAVE fuse bit set and no issues with erased eeprom when loading a new sketch, also see below:

Arduino Uno with optiboot:

uno.bootloader.tool=avrdude
uno.bootloader.low_fuses=0xFF
uno.bootloader.high_fuses=0xDE
uno.bootloader.extended_fuses=0xFD
uno.bootloader.unlock_bits=0x3F
uno.bootloader.lock_bits=0x0F
uno.bootloader.file=optiboot/optiboot_atmega328.hex

High fuse (0xDE) does not enable EESAVE.

@mythbai Looks like the node is not actively listening for incoming commands. Please post the full node sketch and node debug log for troubleshooting.

@sirben You can download the library here: https://github.com/tekka007/MySensors/tree/GWonlyHeartbeat

@sirben ok, this feature is currently disabled for GW-only with disabled transport network. I'll prepare a code update: https://github.com/mysensors/MySensors/pull/1273

@sirben Welcome to MySensors! When talking about the heartbeat output - are you referring to the serial debug or tcp/ip output?

@phil2020 Thanks for reporting back. Do you happen to have a full debug log of both nodes incl. GW debug log while assigning ID 255, rebooting and setting new IDs (without random delay) - I'd like to understand why the random token verification failed.

@phil2020 After assigning ID 255 you need to power cycle the node to trigger a new ID request (only for non-static ID defs)