Hi! I bought an BTM-110 Bluetooth module and i couldn't connect to Arduino Duemilanove with Atmega 328 board. I couldn't even find him with laptop or phone. I connect it at Arduino 3.3V ,GND and TX , RX , and i put a voltage divider between TX from Arduino and RX from BLuetooth module to get 3.3V. I put an osciloscope on TX pin from bluetooth and it sends some signals , so i think it's working. I followed this tutorial http://www.instructables.com/id/Cheap-2-Way-Bluetooth-Connection-Between-Arduino-a/?ALLSTEPS What should I try next?
Hi, don't forget that TX and DX are connected to the USB, so even if you see activity it doesn't mean it comes from the module. I don't have that module so I can only provide some general suggestions.
That instructable assumes that the module starts as a master, advertises its name and accept connections. Is this the default state of the module, or the result of a previous configuration? I don't know, but I would think that the module needs to be configured. Anyway, here is what I would do:
carefully study the command set of your module. There is no standard set of commands, you need to know the ones that work for you. Look especially for the command that set the module state to master and put it in inquiry mode.
prepare a small sketch which, after a delay (allowing the module to start up, let's say 3 secs), sends (print) the commands (or, just start from one) to Serial. Take care of properly terminating the command (e.g., \r\n, if the manual says so). After sending the command the sketch waits for Serial.available() - a response from the module, and takes some visible action such as blinking an LED if there is a response.
disconnect the Tx and Rx going to the module, connect the Usb and upload the sketch.
disconnect the Usb and reconnect Tx and Rx to the module, power up, see if the led blinks, see if you can find the module from your other bluetooth devices.
If that works you may continue adding configuration options to your sketch, until you are able to run the one from the instructable.