A Forum at Sky's Edge

hi,

relate to the ATmega2560 issue:
ATmega2560-8mhz using crystal 7.3728MHz (USART max. 230K baud)
ATmega2560-16mhz using crystal 14.7456MHz (USART max. 230K baud)
safe usart speed 115200

if you are thinking on upgrading the hardware or for new projects,
a good replacement for the ATmega would be an ESP32WROOM from espressif.

price is a lot cheaper
available in SOCs or modules
32bit cpu dual core 240mhz
arduino compatible (librairies) epaper lcd , color lcd, spi ,uart, etc..
wifi 2.4ghz and bluetooth 4.2 with BT classic audio
bootloader

from digikey
https://www.digikey.com/en/products/fil ... MSM3IQqtqA

I can help in software if need.

note:
ESP32 use Bluetooth 4.2 BT classic audio and BT LE (audio library available)
ESP32-S3 use Bluetooth 5.0 LE without BT classic audio (NO audio library available for the moment)

I'm not a huge fan of the atmegas in general just because they're kind of expensive for not a lot of functionality. ESP32 or RP2040 would've worked just fine, but I think Justine wanted to copy what Arduino was doing ¯\_(ツ)_/¯

Whatever, it works

and yeah we're going for 7.3728 MHz for the 2560V