How to get 32u4 arduino to ignore DTR for USB Serial?
Hmm, upon further review, digging through the Arduino source for the USB serial code, it looks to me like the DTR check is at line 224 (first line of size_t Serial_::write(const uint8_t *buffer, size_t size)). I’m not terribly optimistic about disabling it (you’ll probably flood some buffer), but it might be worth a try.