Using HC-05 Bluetooth module with STEVAL-MKI109V3 + STEVAL-MKI208V1K

[lostraj24]

Hello ST Team,

We are using the STEVAL-MKI109V3 as the motherboard and STEVAL-MKI208V1K (IIS3DWB vibration sensor) as the daughter board.

We currently communicate using the USB virtual COM port at 115200 baud and send ASCII commands such as:

*SETDB208V1

*ZOFF

*W10A2

*DEBUG

*STOP

These commands work correctly over USB.

Objective:

We would like to print the data serially using the same commands, but over Bluetooth, not USB.

The accessory board STEVAL-MKI115V1 is no longer available in the market.

We tried using an HC-05 Bluetooth UART module, connecting it to BT_TX and BT_RX (J9 connector), but it did not work, so the default MKI109V3 firmware support UART input/output on the BT_TX / BT_RX pins ?

 

• Can we connect a standard Bluetooth SPP module (HC-05 or similar) to BT_TX / BT_RX and send the same ASCII commands (*SETDB208V1, etc.) wirelessly?
• Or is USB the only supported communication interface in the default firmware for command parsing and data streaming?

Any guidance or documentation regarding UART usage or supported alternative Bluetooth modules would be greatly appreciated.

Thank you.

Raj

[Peter BENSCH]

Welcome @lostraj24, to the community!

Not only was the STEVAL-MKI115V1 discontinued a long time ago, but also the STEVAL-MKI109V3, but for the latter there is a replacement, the STEVAL-MKI109D, on whose DIL24 socket the same sensors can be plugged in.

It should be noted that the BT module SPBT2532C2.AT was used on the STEVAL-MKI115V1, which was also discontinued many years ago. However, it was not controlled via RX and TX (software handshake), but via CTS/RTS (hardware handshake). Therefore you would have to simulate the hardware handshake using the CTS/RTS lines.

Hope that helps?

Regards
/Peter

[lostraj24]

Hi Peter,

Thank you for the explanation. I tried to work based on the solution you described, but unfortunately it is not working for me. I would like to better understand how the RTS/CTS hardware handshaking works in this case.

Here is what I have done so far:

• I am using a USB to UART TTL converter (FT232RL, 5V / 3.3V)

• I connected it to STEVAL-MKI109V3 using the following signals:

  • TX

  • RX

  • RTS

  • CTS

  • GND

• On the PC side, I am using a serial terminal (for example Docklight) and I enabled the RTS/CTS hardware handshaking option.

• However, I do not see any data communication at all.

• I also tried providing an external 5V power supply on the J4 connector, and then repeated the same procedure, but the result is the same — still no communication.

Could you please explain how RTS/CTS handshaking is supposed to work on this board?
Any guidance, signal description, or timing requirements would be very helpful.

Thanks in advance for your support.

Regards,
RAJ