problem calibrating HC-05(ZS-040)

[jonathanbyrn]

Hi,
I am trying to calibrate my bluetooth but it is not being detected in the calibration. I have read through the documentation and forum and I am doing the following:
[ol]
[li]Because it is HC05, I am connecting the 3.3v and the key pin for initial calibration (see picture)[/li]
[li]I have checked the voltage at the key pin (EN) and it is 3.3V[/li]
[li]The board is fully disconnected (USB and battery)[/li]
[li]I press the button on the bluetooth board and hold it while I connect the battery[/li]
[li] the board powers up and the light is flashing every 2 seconds[/li]
[li]I connect the USB and start the setup mode[/li]
[li]It goes through the different baud rates and ends in an error[/li]
[/ol]

Is there anything I am doing wrong in this setup, or anything I can do to debug the board?

 

[jonathanbyrn]

So I have taken the bluetooth module off the board and have been testing it separately. I have been working through the following tutorial: http://www.martyncurrey.com/arduino-with-hc-05-bluetooth-module-in-slave-mode/
I can get it to connect with my phone and send messages from the arduino to the bluetooth terminal app on my phone, but I cannot send messages from my phone to the module.

I then connected it to an oscilloscope to check what is being sent from the module. There is a signal being sent on the TX but it is only 1.5V and not enough to register on the arduino. Is this because it is a faulty component, or is there a setting I should change?

 

[nero76]

Just to be sure: There is 5v on the VCC pin, but only 1.5V on the TXD pin? That is odd...
https://www.marotronics.de/media/image/product/15/lg/hc-05-wireless-bluetooth-rf-transceiver-module-serial-rs232-fuer-arduino~2.jpg

 

[jonathanbyrn]

Yes, I double checked and there is 5V at the VCC pin. It works when sending from the serial monitor to my phone but nothing is coming off the TX pin. Even if it is in AT mode (2 second flash) I cannot get an OK for an AT command.

 

[nero76]

The default baud rate is different from module to module. You can use Ardumower Bluetooth programming via USB serial console (choose 'd' for main menu, then '3' for communications menu, then '3' for BT module config) to re-program the module for the Ardumower 19200 baud baudrate. Can you try it?

http://wiki.ardumower.de/index.php?title=Bluetooth#Steps

 

[jonathanbyrn]

The bt module config function returns nothing despite going through all the baud rates (I tried both express and full versions to iterate through the baud rates). When I tested it using my phone my phone and the tutorial linked above, it connected and I was able to send messages to my phone so I think it is connecting correctly. The problem is that the module cannot send anything down the TX pin. When I connected it to an oscilloscope it registered a small signal but it was less than 1.5v and was not registered by the arduino.