Hi @teohell @weatherman ,
I did some research today. The HM10 with firmware V545 can also work with service UUID 0xFFF0. So our BlueDuino can play with HM10 module directly.
Please try these commands. I tested and they sent data each other.
AT+FFE21 did the trick. It enable two characteristics 0xFFF1 (notify) and 0xFFF2 (write). It's compatible with our BlueDuino.