Install avr-libc via homebrew on mac:

brew tap osx-cross/avr
brew install avr-libc

Install radare2

brew install radare2


Convert the hex to bin

avr-objcopy –I ihex –O binary hello.hex hello.bin

load with radare2

r2 -a avr hello.bin

or output assembly, for the atmega328p:

avr-objdump -j .sec1 -d -m avr5 test.hex

where -m specifies the architecture of your chip from: