I want to use the Bluetooth on my project. HC-05 is my Bluetooth. I could use it on my Arduino Uno. The connection is Vcc(HC-05) to 5V(Arduino Uno), GND(HC-05) to GND(Arduino Uno), TX(HC-05) to RX(Arduino Uno), and RX(HC-05) to TX(Arduino Uno) . In this way, I could pair the Bluetooth to my computer and get the communication between Serial monitor and Arduino Uno. I tried to do the same way with my Seeeduino Xiao. I could pair the Bluetooth with my computer. When I open the Serial monitor with the Bluetooth COM, I could observe that the HC-05 is connected to my computer. However, the Seeeduino could not print output on the Serial monitor through HC-05. I did some measurement and found TX =RX=3.3V on Arduino Uno when the HC-05 is connected to the computer. However, the result is difference on Seeeduino Xiao. The RX=3.3V and TX=0V. Any suggestion? Thx for the help!
Seeed Xiaomi supports software serial. But keep the baud rate 9600 or 15200. Don’t set it higher. At higher rate the TX fails and at highest rate both RX and TX fails. Hope this helps