Bluetooth Serial Communications with the APM

I've heard some people mention using bluetooth to communicate with microcontrollers as replacement for a serial or USB & FTDI. Recently some small bluetooth serial modules have become available from large electronics retailers and smaller ones that operate on large internet auction websites. They can be purchased now for just a few bucks. The module has all the bluetooth components integrated and takes 3 volt TTL level RS232 signals. It comes in a surface mountable pcb package, however breakout boards are available that have easily hand solderable headers, and a 3V regulator etc:

Although these modules are 3V, they will work with the 5V APM, so long as there is at least a 1K resistor on the RXD (which is what the 5V TX line on the APM will drive). The 3V signal from the module to the APM is OK as it is.

Starting communication is a matter of pairing with the device which comes up as 'linvor', then enter the default pin (0000). Add a com port to the device - mine comes up as COM8. The baud rate is 9600 by default, but can be changed with a special AT command, I set mine to 57600.

The range is nowhere near the XBees of course, however it is useful to configure PIDS in the back yard etc - it's also nice and cheap.

There is some information in a multiwii discussion here. Also an interesting page with some useful technical info here.

You need to be a member of diydrones to add comments!

Join diydrones

Comments

druckgott October 15, 2011 at 12:34pm

I have also orderd one.

Could I also use this this my android phone and the software for arducotper?
Developer

Mark Colwell September 18, 2011 at 3:37pm

I bought 2 and a 1 amp wifi booster all for $40, hope they all work...
Andrew Radford September 18, 2011 at 2:08pm

@ Max:

Baud rate is changed by using an AT command - this must be done directly connected to the module, not over BT - so I just used the FTDI and some jumper cables. Also the command must be sent when the module is not 'connected' - maybe worth just un-pairing to be sure.

The command I used (using a terminal program like Hyperterm) was

AT + BAUD7

At that point the module would not talk to me any more because I had to re connect in the new baud rate of 57600. There is some more info on the link I posted - you may have to use google translate!
Roterdan Macedo September 18, 2011 at 2:00pm

Hi all,

I already use one Xbee Bluetooth module. I only chage the Xbee module when I need to use the datalink in bluetooth mode.

I use this module http://www.dfrobot.com/index.php?route=product/product&path=45&...
Developer

Max Levine September 18, 2011 at 1:36pm

Andrew, can you please share more info on how to change the baud rate ?
YureZzZ September 18, 2011 at 2:14am

I've used the same way when I had no Xbee. For now Xbee is doing everything and bluetooth module is going to my ardurover =)
Andrew Radford September 18, 2011 at 1:13am

The sparkfun board will have a different pinout, but for these boards it is

APM Bluetooth module

GND --- GND

5V --- Vin

TX -- (resistor) -- RX

RX ---- TX

The module I bought came with a grey IDC ribbon cable with an inline connector on one end, and individual pin sockets on the other. This was handy because the pin order of the telemetry port is different to that of the bluetooth module.
Markus Wolfarth September 17, 2011 at 4:15pm

Hi Andrew, thank you very much for this information! Please, can you post more Informations how you connect this module to the APM? I want to connect a Sparkfun Mate Silver to my Arducopter, but i found no Informations how to do that (and i don't want to damage my APM Hardware).

Regards

Markus
Sebastian Gralla September 17, 2011 at 4:08pm

was just searching for a bluetooth module -> ordered!

thx :D

of 4

This reply was deleted.