Programmer is not responding


I have a strange problem, I’m using Atmega2560V with internal oscillator.

If I set the fuses (bootloader) to 4MHz internally and in platformio.ini I set the flag f_cpu= 4000000L.
On the serial (9600) I get some strange characters like


If I set 8000000L on platformio.ini but keep 4MHz on Fuse, it works.

But if I set 8MHz on Fuse and keep 8000000L, serial monitor tells me:

avrdude error: programmer is not responding
avrdude warning: attempt 1 of 10: not in sync: resp=0x00

I tried to load a blink led sckatch from Arduino IDE at 8MHz and it works.

My platformio.ini fili is

platform = atmelavr
board = ATmega2560
framework = arduino

lib_deps = ---------

board_hardware.bod = disabled
upload_speed = 9600
monitor_speed = 9600
board_build.f_cpu = 4000000L
board_hardware.oscillator = internal
upload_port = COM3
monitor_port = COM3