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Pmod BT2 Issues


I have been working hard to understand the RN-42 device on the Pmod BT-2 with very little success.

The Goal: To implement a pair of BT2 modules in a BAN (body area network) under PIC micro control at both ends.

The present Scenario: I have been trying to take a modular approach to this project. Currently, I have two BT2 modules each plugged into a  Microchip explorer8 Pmod socket on two separate boards. At present there is no active MCU on either board, instead I have patched the RxD and TxD to the pins of the USB to Serial interface. In this way, I have been able to access the modules via PuTTY.  CTS is at ground and RTS is at 3.3v.

What I have done so far: I have initialized the BT2 to factory defaults and then tried either the software setup or the jumper setup to make one a master and one a slave. When I send the "I" command from PuTTY each radio sees the other's MAC address. Over several iterations I have used the SR to set the remote address of the master and slave to each other.  I have then tried to send the C command either with or without following it with the MAC address of the opposite radio . I get the message "TRYING" and then a " connection failed" message. I have also used the GR  command to confirm the remote addresses were set correctly. I get no solid green light.

When using the jumper method on two BT2's that have been reset with then no REM addresses set,With jumpers J2 and J3  set on one BT2  and only J2 set on the other apparently nothing happens. I was expecting  to see the flashing green light go solid indicating a pairing had occurred.

When I look at the Bluetooth window on my Win10 tablet I do see both modules show up. At that point my tablet shows me an apparent random 6 digit number. when I acknowledge this number the tablet then pairs with the radio. Because of my minimalist test setup, when I pair the radio with my tablet which is physically connected to my desktop machine I haven't been able to figure out how to confirm it is actually connected, as even after pairing I get no solid green light.

Clearly I am missing something. Am I wrong to assume that I should get these radios to connect in such a minimalist setup? I believe that because I will be sending one short Ascii string when implemented under MCU control that these are the proper devices to use for an "invisible wire" setup.  Should I be using the HID 0000 keyboard profile? I do not need or want the radios to connect to anything else except each other. 

Please help!

Thank you,


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Hi NeilRG,

This is an interesting project! I am looking into your questions about the PmodBT2. I will get back to you as soon as i am able. 



Update: One of my co-works pointed out this tutorial.

Edited by jpeyron

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The link you provided had the key element I was not getting. Authentication has to be turned off.

Thank you VERY much.

Here are some useful points I learned:

After sending $$$ to the module and getting the CMD back from the BT2, send + to turn echo mode on.

This makes it easier to be sure you are entering the MAC addresses correctly.

The command mode (CMD) does not allow you to use the backspace key if you make a mistake typing the MAC address in the SR, mode just hit <enter> and repeat the step.

In my application I set the Bonding flag SX,1 to enable bonding since I do not want the modules to connect to anything else. Note that if you change the bonding value off to on or on to off the Rem value set with the Set Remote SR,<mac address> is lost .

Whatever changes you make , you will need to send the reboot R,1 command to reboot the module. Confirming the value without rebooting by using the D command is not sufficient.

Contrary to what the Roving Network literature says on this module when they are paired the RED led is solid and the GREEN led goes out.

Once they are paired and Bonded the connection works better if the slave module is powered on first and then the master. It is not necessary to try to have to power them up at the same time.

If you have your terminal program (I used PuTTY) on two separate machines and one BT2 connected to each machine, if you open PuTTY and have both the CTS and RTS tied to ground you can type on either machine and see it in the others PuTTY window. To quote Daffy Duck "Oh Joy, Oh Rapture!!!"


Edited by NeilRG
I wanted to put this in the forum. Originally I found I had inadvertently just sent it to Mr. Peyron

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