Help needed using BT4502 Bluetooth module with Seeduino XIAO

Trying to use BT4502 with Seeduino. Is there any example or getting started tutorial for BT4502 ?
I have connected Seeduino and BT4502 GND pins Seeduino 3.3V to BT4502 VDD pin and TX to RX , RX to TX together.
BT4502 mac address can be seen in my Phone Bluetooth devices, but it refuses to pair.
Also I opened Arduino IDE (with USB cable connected) and tried to send AT commands via Serial Monitor to BT4502, but the Serial monitor just hangs.
Any ideas how can I get this working ?

Hi @heikki728 You can find the BT4502 documents here:

You can send out the code suspended in your serial port, and I may be able to help you. @heikki728

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I have read the linked document, but it does not give answers to the following questions :
If BT4502 powerline (3.3V) is connected, I can see Bluetooth device in my Android tablet, but it refuses to get paired (does not ask password). So what is the trick to get it paired ?
Secondly, if Seeduino pin 6 (TX) is connected to BT4502 RX and Seeduino pin 7 (RX) to TX in 4502, should it be possible to send configuration commands to 4502
for example:
SoftwareSerial mySerial(7, 6); // RX=7, TX=6 Seeduino
mySerial.write(“TTM: NAM-?”)

I find it doesn’t respond if you have the space between : and N, try “TTM:NAM-?\r\n\0” instead.

Discuss it together here.

I have a similar issue. I am able to pair the Bluetooth. However, I failed to transmit data from Seeeduino Xiao to computer’s serial monitor through Bluetooth. Any suggestion? Thank you!

Is there any document on how to interface a PIC micro to the BT4502 or EMB1061 module ?
I just want one module to transmit a packet of data and the other module to receive this packet.
The Datasheets do not give complete details for the UART / SPI interface !

Help appreciated !

I forgot to use BT4502 Bluetooth. I recommend to look at this Sparkfun product

It is much better documented than BT4502 and everything works fine with my Arduino Nano

The BlueSMiRF (or even the RN42 Module used in this) are way too expensive !!
I need something in the $2-$3 range for the BT Module.

The EMB1061 ($2.50) is ideally suited, but no information or documentation…

I need a simple & cheap bi-directional Serial to Bluetooth convertor !

I’m also trying to interface this bluetooth module with arduino. But I’m no good at coding. Has anyone mange to get this to work? Also I’m wondering which pins do I need to connect on the pins besides the VDD and ground plus the rx and tx?


Hi, I do not recommend to use BT4502 (too tricky and undocumented), BlueSMiRF is also depreciated now.
Please consider using arduino with integrated Bluetooth
(Arduino Nano BLE or Arduino RP2040Connect).
Programming in the Arduino side is much easier than serial communication.

The only problem is that I’m working on a watch project and this would be great for it because of the size. and location it will go into.