RN-41 bluetooth break out board not responding

Projects Networking, Protocols, and Devices
1

Hey guys. I'm having a problem with the RN-41 bluetooth serial board found here Bluetooth Module Breakout - Roving Networks (RN-41) - WRL-10559 - SparkFun Electronics. Although the board connects to my computer as a bluetooth device, attempts to talk to the arduino over the serial monitor in the arduino IDE fail, as do attempts to upload data. The details are as follows:

Using windows 7 pro, arduino ide 1.0.1, and the Duemilanove board. I have a prototyping board with a mini breadboard on top, into which the breakout bluetooth module is inserted.
The ground, 3.3v pins, and RX/TX pins are connected from the arduino to the RN-41. As far as I know, these are the only connections you need, and the TX/RX pins are swapped (though I have tried TX->TX and RX->RX in case I misunderstood the labeling). I believe all other required circuitry is built into the breakout board.
The software on the arduino is a simple test serial program that echos whatever characters are sent to it over the serial port, , which works fine when plugged in via USB. The baud rate is 9600.

First, I search for bluetooth devices. My computer finds it as FireFly-66EA. I add it without pairing, and it shows up as a serial over bluetooth device, COM 7, with a baud rate of 9600. If I then go into the device manager, it shows both COM 7 and COM 8 as having been created. Then when I open up the arduino ide, my computer alerts me that a device is trying to connect from a little word bubble down by the systray. I click that, it asks me to put in a pairing code, and I put '1234'. It tells me the devices has successfully connected (which is odd, because I thought it was already connected). Then the arduino IDE finishes starting up. It sees COM 8 (but not COM 7) which I connect to.

From there, if I attempt to upload code to the arduino, it pauses at the uploading stage, and I have to close the IDE, and then close another process in task manager to free up the com port again. if I try to send any data via the serial monitor, the whole IDE freezes up completely, and I cannot even close it. The RX/TX lights on the arduino do not blink, indicating no data between the bluetooth device and arduino is being passed.

Right now money dictates I have to work with what I've got, so I would very much like to get this device working. If anyone sees any errors in my procedure or has had a similar experience they were able to remedy, please help! Your time is very much appreciated. Thank you :slight_smile:

2

This line from the user manual of your device might give you a hint, what you're doing wrong:

Baud rate 115,200

Section 3.2, page 5

3

Thanks for the response. But I did end up changing the baud rate on the device. Snce posting my problem, I have delved very deeply into the manual and schematics. It was given to me by a friend who said it was read to go with no other circuitry, but suspecting otherwise I've made some progress. Still not working though.

The device itself seems to be working. I connected to it through putty. Changed the baud rate to 9600. Further, I bridged the device's the RX and TX pins so I could make sure that action mode was working, and it does. Whatever I type is echoed right back at me. I hooked up an LED to PIO2, and it lights up whenever I have a connection to the BT device.

When I hook the RX/TX pins to the arduino instead though (using two resistors as a voltage divider from the 5v arduino TX to the 3.3 volt RN41 RX), I still can't seem to communicate. I've tried using putty and a C# program I wrote, because the arduino IDE does not see the bluetooth serial port, which this article: http://letsmakerobots.com/node/30915, suggests might be an issue with the way the IDE scans for serial ports. With either putty or my own software, my BT connection LED lights up, but the arduino never responds or sends data.

Additionally I tried adding a long delay before the arduino calls Serial.begin(), thinking maybe the device takes longer to establish itself as a serial device with the computer than the arduino takes to start up, cause Serial.begin() to error. Not sure if there's any truth to this but I felt it was worth a shot.

I've narrowed it down quite a bit since yesterday morning but now I'm at a loss again. Any ideas?

4

How did you connect it through putty? What type of cable did you use?