Thanks for sharing your work. I tried it without voice detection. BT is paired with my phone but apperently no serial data is send. If I try to send "1" or "2" with my computer connected in bt, using putty the led switch on and off correctly so the hardware and arduino sketch is ok. my problem is coming from app inventor. what is button 1 set and number for? is the real value 1 and 2 are send or ascii value. I tried with mega 2560 with external power and connect rx and tx to serial 0