bluetooth relay driver project

Community Project Proposal
#1

Hi all.

I am a tinkerer, but have no formal training, so I tend to ask questions in order to be sure of an appropriate direction to take. I love building gadgets, but sometimes my ideas are beyond the basic knowledge that I have attained.

Here’s what I want to accomplish, I’m hoping that someone can recommend the appropriate Bluetooth module and configuration (if it seems possible).

I want to turn on and off a small 12V motor using commands from my cellular phone. I am a software developer, so I understand and have written a basic program for my cellular phone which will connect to a comm. port, open it, and set the DTR and RTS lines high or low. This change 9v fluctuation on pins 4 and 7 can be used to control a relay circuit that opens and closes the power source to my motor.

I see commercial Bluetooth serial adaptors that appear to have the functionality that I need:
9v external power source to ensure the 9v power to drive the relay circuit
Supported DTR/RTS
Supported connection to cellular phone as a serial port with no additional software required

I’m wondering if one of the Bluetooth serial port modules offered by this website would offer a similar drop-in functionality by allowing me to power it with 9v and simply search for the BT device and connect and start sending DTR and RTS high/low commands?

Any recommendations on accomplishing what I’m looking for?

#2

The voltage used by bluetooth module is between 2.7v-4.2v, so its output could not get 9v.
The module hasn’t DTR port, it use Tx and Rx to send or receive data from other bluetooth.
The CTS and RTS port is controlled by the module itself as the indication for the user, but they
could not controlled by user directly.

If you really want to use the bluetooth to control your circuit, probably you need to add a simple MCU.

#3

thanks for the tip.

So now I’m working on learning what I need to do to use an atmega to control my process, and started looking at a variety of ways to interface with different serial bluetooth devices. I’m wondering if anybody can tell me what the difference is between the bluetooth serial devices on this site are, and something like the bluesmirf modules from sparkfun that cost about 3 times the price? Seems odd to be that much more pricey, unless I am missing some major pieces that I’m going to need to work with these modules, which are already resolved in the bluesmirf.

tia for any advice